add password-reset flow: request endpoint + reset page + login link (shared OneTimeToken)

app/templates/admin/login.php

@@ -14,6 +14,11 @@
                     <button type="submit" class="btn btn--primary">Se connecter</button>
                 </div>
             </form>
+
+            <form method="post" action="/admin/request-reset.php" class="admin-form" style="margin-top:var(--space-s)">
+                <input type="hidden" name="csrf_token" value="<?= htmlspecialchars($_SESSION['csrf_token'] ?? '') ?>">
+                <button type="submit" class="btn btn--muted">Mot de passe oublié ?</button>
+            </form>
         </div>
     </div>
 </main>