feat: My Account — modifier username, nom, email, mot de passe

Backend:
- PUT /api/settings/account (full_name, login, email, password)
- Vérifie que le username n'est pas déjà pris
- Password min 6 caractères

Frontend (Settings → My Account):
- Champs éditables: Username, Full name, Email
- Section Change password avec toggle 👁/🙈
- Bouton Save changes + Update password
- Message de confirmation ✓ / ✗ avec timeout 3s

app/routers/dashboard.py

@@ -1361,3 +1361,39 @@ async def search_by_tags(request: Request, tags: str = ""):
             "size_display": _format_size(size),
         })
     return {"items": items}
+
+
+# ── Account update ──
+@router.put("/api/settings/account")
+async def update_account(request: Request):
+    """Update current user's profile: full_name, login, email, password."""
+    import json
+    from app.password_utils import hash_password
+    user = SessionManager.decode_session(request.cookies.get("flowdeck_session", ""))
+    if not user:
+        return JSONResponse({"error": "Not authenticated"}, status_code=401)
+    try:
+        body = await request.json()
+    except Exception:
+        body = {}
+    with get_conn() as conn:
+        uid = user["id"]
+        if "full_name" in body:
+            conn.execute("UPDATE users SET full_name=? WHERE id=?", (body["full_name"].strip(), uid))
+        if "login" in body:
+            new_login = body["login"].strip()
+            if new_login and new_login != user.get("login"):
+                existing = conn.execute("SELECT id FROM users WHERE login=? AND id!=?", (new_login, uid)).fetchone()
+                if existing:
+                    return JSONResponse({"error": "Username already taken"}, status_code=409)
+                conn.execute("UPDATE users SET login=? WHERE id=?", (new_login, uid))
+        if "email" in body:
+            conn.execute("UPDATE users SET email=? WHERE id=?", (body["email"].strip(), uid))
+        if "password" in body and body["password"].strip():
+            pw = body["password"].strip()
+            if len(pw) < 6:
+                return JSONResponse({"error": "Password must be at least 6 characters"}, status_code=400)
+            conn.execute("UPDATE users SET password_hash=? WHERE id=?", (hash_password(pw), uid))
+        conn.commit()
+        row = conn.execute("SELECT id, login, full_name, email, is_admin FROM users WHERE id=?", (uid,)).fetchone()
+    return {"status": "ok", "user": dict(row)}