feat: fix auth, provider health checks, search, and redesign UI

- Fix register/login: dict-style access on UserTable ORM objects
- Fix HTMX auth: inject JWT token in all HTMX request headers
- Fix FS7 search: use DLE AJAX endpoint /engine/ajax/search.php
- Fix ZT search: use ?p=series&search=QUERY (not DLE format)
- Fix provider health: load hardcoded providers + domain manager
- Add self.id to all anime/series providers
- Redesign homepage: Netflix-style horizontal scroll cards (.hc)
- Redesign search results: grouped by title, poster + synopsis + 3 buttons
- Add Télécharger dropdown: season download + episode picker
- Fix navbar CSS: restore .tabs flex layout, remove orphan rules
- Fix HTMX spinner: remove inline display:none, use CSS indicator
- Add AGENTS.md files across project for developer documentation

templates/components/header.html

@@ -9,8 +9,9 @@
             <span style="color: #fff; font-size: 14px;">Connecté en tant que <strong x-text="username" style="color: var(--primary);">-</strong></span>
         </div>
         <button class="btn btn-secondary btn-small" 
+                onclick="removeToken(); isAuthenticated = false"
                 hx-post="/api/auth/logout"
-                hx-on::after-request="isAuthenticated = false; window.location.reload()">
+                hx-on::after-request="window.location.href = '/login'">
             🚪 Déconnexion
         </button>
     </div>