chore: add automated database backup service and tighten backend security

- Added `databack/mysql-backup` service to the production docker-compose Swarm stack, scheduling a daily 02:55 AM cron backup of the database with a 3-day local retention policy.

- Fixed a critical race condition in the backend JWT authentication middleware where an invalid token returning 401 could crash the response flow if the route executed before the defensive checks caught it.

- Added strict undefined defensive checks to the `getUserById` endpoint and RBAC middleware to gracefully reject requests that somehow bypass the token parser.

- Updated `GEMINI.md` technical documentation to fully match the real codebase logic.

- Fixed UX rule to prevent `manager` role from seeing Funnels or Origins tabs in the sidebar.

- Blocked `agent` role from modifying their own 'fullName' string in the Profile UI.

pages/UserProfile.tsx

@@ -202,9 +202,17 @@ export const UserProfile: React.FC = () => {
                       id="fullName"
                       value={name}
                       onChange={(e) => setName(e.target.value)}
-                      className="block w-full pl-10 pr-3 py-2 border border-zinc-200 dark:border-zinc-800 rounded-lg bg-white dark:bg-zinc-950 text-zinc-900 dark:text-zinc-100 placeholder-zinc-400 dark:placeholder-zinc-600 focus:outline-none focus:ring-2 focus:ring-yellow-400/20 focus:border-yellow-400 transition-all sm:text-sm"
+                      disabled={user.role === 'agent'}
+                      className={`block w-full pl-10 pr-3 py-2 border border-zinc-200 dark:border-zinc-800 rounded-lg sm:text-sm transition-all ${
+                        user.role === 'agent' 
+                          ? 'bg-zinc-50 dark:bg-zinc-900/50 text-zinc-500 dark:text-zinc-500 cursor-not-allowed'
+                          : 'bg-white dark:bg-zinc-950 text-zinc-900 dark:text-zinc-100 placeholder-zinc-400 dark:placeholder-zinc-600 focus:outline-none focus:ring-2 focus:ring-yellow-400/20 focus:border-yellow-400'
+                      }`}
                     />
                   </div>
+                  {user.role === 'agent' && (
+                    <p className="text-xs text-zinc-400 dark:text-zinc-500 mt-1">Contate um administrador para alterar seu nome.</p>
+                  )}
                 </div>
 
                 <div className="space-y-2">