chore : ajouter fichiers non versionnés (migrations SQL, 404, PROJET.md)

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

database/migration_012_users.sql

@@ -0,0 +1,8 @@
+CREATE TABLE IF NOT EXISTS users (
+    id                  SERIAL PRIMARY KEY,
+    email               TEXT    NOT NULL UNIQUE,
+    password_hash       TEXT    NOT NULL,
+    is_active           BOOLEAN NOT NULL DEFAULT TRUE,
+    updated_at          TIMESTAMP,
+    password_changed_at TIMESTAMP
+);