feat #58 : wizard multi-étapes création/édition d'article

Remplace le formulaire unique par un wizard 5 étapes (création) et
6 étapes (édition) avec auto-sauvegarde en brouillon, détection de
tags depuis le texte (TagSuggester), aperçu SEO, diff avant validation
et plan Markdown dynamique dans l'éditeur.

Détail des changements :
- ArticleManager : +6 méthodes (updatePartialMeta, saveDraftOverlay,
  getDraftOverlay, hasDraftOverlay, discardDraftOverlay, commitDraftOverlay)
- .htaccess : routes /new/{uuid}/{1-5} et /edit/{uuid}/{1-6}
- index.php : cases create et edit réécrits en switch($step),
  nouveau case autosave_draft et edit_discard_draft
- assets/js/wizard.js : autosave debounce, auto-resize textarea,
  scroll curseur, plan TOC dynamique, toggle pills tags
- templates/wizard/ : nav.php + step1..6.php

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

templates/wizard/step1.php

@@ -0,0 +1,182 @@
+<?php
+// Attendu : $mode, $step, $totalSteps, $uuid, $formAction, $title, $content (article),
+//           $existingFiles, $insertUrl, $article, $errors
+ob_start();
+$_wizUuid   = $uuid ?? '';
+$_backHref  = '/';
+$_hasUuid   = $_wizUuid !== '';
+?>
+<div id="vl-page"
+     data-uuid="<?= htmlspecialchars($_wizUuid) ?>"
+     data-insert-url="<?= htmlspecialchars($insertUrl ?? '') ?>"
+     data-autosave-url="<?= $mode === 'edit'
+         ? '/?action=autosave_draft&uuid=' . rawurlencode($_wizUuid)
+         : '/?action=autosave&uuid=' . rawurlencode($_wizUuid) ?>"
+     hidden></div>
+
+<form method="POST" action="<?= htmlspecialchars($formAction) ?>" enctype="multipart/form-data">
+
+<!-- En-tête avec boutons ────────────────────────────────────────────────── -->
+<div class="d-flex align-items-center justify-content-between gap-3 mb-4 flex-wrap">
+    <div>
+        <h1 class="h4 mb-0"><?= $mode === 'create' ? 'Nouvel article' : htmlspecialchars('Modifier — ' . ($article['title'] ?? '')) ?></h1>
+        <?php if ($_hasUuid): ?>
+        <span id="autosave-indicator" class="text-muted small"></span>
+        <?php endif; ?>
+    </div>
+    <div class="d-flex gap-2 align-items-center">
+        <a href="<?= htmlspecialchars($_backHref) ?>" class="btn btn-outline-secondary btn-sm">Annuler</a>
+        <button type="submit" class="btn btn-primary">Suivant →</button>
+    </div>
+</div>
+
+<?php if (!empty($errors)): ?>
+<div class="alert alert-danger mb-3"><ul class="mb-0"><?php foreach ($errors as $_e): ?><li><?= htmlspecialchars($_e) ?></li><?php endforeach; ?></ul></div>
+<?php endif; ?>
+
+<?php include __DIR__ . '/nav.php'; ?>
+
+<div class="row g-3 align-items-start">
+<div class="col-lg-9">
+
+<!-- Titre ─────────────────────────────────────────────────────────────── -->
+<div class="mb-3">
+    <label for="wz-title" class="form-label fw-semibold">Titre</label>
+    <input type="text" class="form-control form-control-lg" id="wz-title" name="title" required
+           value="<?= htmlspecialchars($title ?? '') ?>"
+           placeholder="Titre de l'article…">
+</div>
+
+<!-- Contenu ──────────────────────────────────────────────────────────── -->
+<div class="mb-3">
+    <label for="wz-content" class="form-label fw-semibold">Contenu <small class="text-muted fw-normal">(Markdown)</small></label>
+    <textarea class="form-control font-monospace" id="wz-content" name="content" rows="18"
+              style="min-height:320px"><?= htmlspecialchars($content ?? '') ?></textarea>
+</div>
+
+</div><!-- /col-lg-9 -->
+
+<!-- Plan (TOC dynamique) ───────────────────────────────────────────────── -->
+<div class="col-lg-3 d-none d-lg-block">
+    <div class="position-sticky" style="top:1rem">
+        <div class="card border-secondary-subtle">
+            <div class="card-header bg-transparent py-2 small fw-semibold text-muted">Plan</div>
+            <div class="card-body p-2" style="max-height:80vh;overflow-y:auto">
+                <ul id="wz-toc-list" class="list-unstyled mb-0"></ul>
+            </div>
+        </div>
+    </div>
+</div>
+</div><!-- /row -->
+
+<!-- Fichiers / Import ─────────────────────────────────────────────────── -->
+<?php if (!$_hasUuid): ?>
+<div class="mb-4">
+    <label for="files" class="form-label fw-semibold">Ajouter des fichiers <small class="text-muted fw-normal">(optionnel)</small></label>
+    <input type="file" class="form-control" id="files" name="files[]" multiple>
+    <div class="form-text">Les fichiers seront attachés à l'article après création.</div>
+</div>
+<?php else: ?>
+<div class="d-flex flex-wrap gap-2 mb-4">
+    <a href="/files/<?= rawurlencode($_wizUuid) ?>/add?back=<?= rawurlencode($formAction) ?>"
+       class="btn btn-outline-secondary">+ Ajouter des fichiers</a>
+    <a href="/import/<?= rawurlencode($_wizUuid) ?>?back=<?= rawurlencode($formAction) ?>"
+       class="btn btn-outline-secondary">+ Importer depuis une URL</a>
+</div>
+
+<?php if (!empty($existingFiles)): ?>
+<?php $_coverFile = ($article ?? [])['cover'] ?? ''; ?>
+<div class="mb-3">
+    <p class="fw-semibold small mb-2">Fichiers attachés (<?= count($existingFiles) ?>)</p>
+    <div class="d-flex flex-wrap gap-2">
+        <?php foreach ($existingFiles as $_fi => $_f):
+            $_fUrl    = '/file?uuid=' . rawurlencode($_wizUuid) . '&name=' . rawurlencode($_f['name']);
+            $_isCover = ($_f['name'] === $_coverFile);
+        ?>
+        <div class="border rounded p-1 d-flex align-items-center gap-2" style="max-width:220px">
+            <?php if ($_f['is_image']): ?>
+            <img src="<?= htmlspecialchars($_fUrl) ?>" alt="" style="width:36px;height:36px;object-fit:cover;border-radius:3px;flex-shrink:0<?= $_isCover ? ';outline:2px solid #0d6efd' : '' ?>">
+            <?php else: ?>
+            <span style="width:36px;text-align:center;font-size:1.1rem;flex-shrink:0"><?= match(true) {
+                str_starts_with($_f['mime'], 'video/') => '🎬',
+                str_starts_with($_f['mime'], 'audio/') => '🎵',
+                $_f['mime'] === 'application/pdf'      => '📑',
+                default                                => '📄',
+            } ?></span>
+            <?php endif; ?>
+            <div class="overflow-hidden flex-grow-1" style="min-width:0">
+                <div class="text-truncate small"><?= htmlspecialchars($_f['name']) ?></div>
+                <div class="d-flex gap-1 mt-1">
+                    <button type="button" class="btn btn-xs btn-outline-secondary"
+                            data-copy-md-name="<?= htmlspecialchars($_f['name']) ?>"
+                            data-copy-md-is-image="<?= $_f['is_image'] ? '1' : '0' ?>"
+                            style="font-size:.65rem;padding:.1rem .35rem">MD</button>
+                    <button type="submit" form="del-file-wz-<?= $_fi ?>"
+                            class="btn btn-xs btn-outline-danger"
+                            data-confirm="Supprimer « <?= htmlspecialchars($_f['name']) ?> » ?"
+                            style="font-size:.65rem;padding:.1rem .35rem">✕</button>
+                </div>
+            </div>
+        </div>
+        <?php endforeach; ?>
+    </div>
+</div>
+
+<?php $_sidebarImgs = array_filter($existingFiles ?? [], fn ($_f) => $_f['is_image']); ?>
+<?php if ($_sidebarImgs): ?>
+<div class="mb-3">
+    <p class="fw-semibold small mb-1">Images <span class="text-muted fw-normal">(clic → insère dans le contenu)</span></p>
+    <div class="d-flex flex-wrap gap-2">
+        <?php foreach ($_sidebarImgs as $_img):
+            $_iUrl = '/file?uuid=' . rawurlencode($_wizUuid) . '&name=' . rawurlencode($_img['name']);
+        ?>
+        <img src="<?= htmlspecialchars($_iUrl) ?>"
+             alt="<?= htmlspecialchars($_img['name']) ?>"
+             title="<?= htmlspecialchars($_img['name']) ?>"
+             data-insert-ref="<?= htmlspecialchars($_img['name']) ?>"
+             style="width:64px;height:64px;object-fit:cover;border-radius:5px;cursor:pointer;border:2px solid transparent;transition:border-color .15s">
+        <?php endforeach; ?>
+    </div>
+</div>
+<?php endif; ?>
+
+<?php $_extLinks = ($article ?? [])['external_links'] ?? []; ?>
+<?php if ($_extLinks): ?>
+<div class="mb-3">
+    <p class="fw-semibold small mb-1">Liens externes</p>
+    <ul class="list-group list-group-flush" style="max-width:480px">
+        <?php foreach ($_extLinks as $_el): ?>
+        <li class="list-group-item px-0 py-1 d-flex align-items-center gap-2 border-0 border-bottom">
+            <span class="flex-grow-1 text-truncate small"
+                  data-insert-ref="<?= htmlspecialchars($_el['url']) ?>"
+                  style="cursor:pointer;color:#0d6efd;text-decoration:underline dotted"
+                  title="<?= htmlspecialchars($_el['url']) ?>"><?= htmlspecialchars($_el['name']) ?></span>
+            <form method="POST" action="/?action=delete_external_link&uuid=<?= rawurlencode($_wizUuid) ?>" class="d-inline flex-shrink-0">
+                <input type="hidden" name="url" value="<?= htmlspecialchars($_el['url']) ?>">
+                <button type="submit" class="btn btn-link btn-sm text-danger p-0 lh-1"
+                        data-confirm="Supprimer ce lien ?" title="Supprimer">✕</button>
+            </form>
+        </li>
+        <?php endforeach; ?>
+    </ul>
+</div>
+<?php endif; ?>
+<?php endif; ?>
+<?php endif; ?>
+
+</form>
+
+<?php if (!empty($existingFiles)): ?>
+<?php foreach ($existingFiles as $_fi => $_f): ?>
+<form id="del-file-wz-<?= $_fi ?>" method="POST"
+      action="/?action=delete_file&uuid=<?= rawurlencode($_wizUuid) ?>&_back=<?= rawurlencode($formAction) ?>">
+    <input type="hidden" name="name" value="<?= htmlspecialchars($_f['name']) ?>">
+</form>
+<?php endforeach; ?>
+<?php endif; ?>
+
+<script src="/assets/js/wizard.js"></script>
+<?php
+$content = ob_get_clean();
+$title   = ($mode === 'create' ? 'Nouvel article' : 'Modifier') . ' — Étape 1/' . $totalSteps;
+include BASE_PATH . '/templates/layout.php';