Update configuration and documentation

- Update .env.example with latest environment variables
- Update deployment and task documentation
- Update backend configuration settings

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Docs/Tasks.md

@@ -1,38 +1,3 @@
-## [MEDIUM] Session secret rotation not implemented
-
-**Where found**
-
-- `backend/app/config.py` — single `session_secret` with no rotation support
-
-**Why this is needed**
-
-If secret leaks, all sessions compromised. No way to invalidate old sessions.
-
-**Goal**
-
-Support gradual secret rotation without forcing logout.
-
-**What to do**
-
-1. Store multiple secrets: current and previous
-2. Accept tokens signed with either key
-3. Re-sign tokens with current secret on validation
-
-**Possible traps and issues**
-
-- Rotation strategy must be documented
-- Metrics needed to track secret usage
-
-**Docs changes needed**
-
-- Update `Docs/Backend-Development.md` § Session Management
-
-**Doc references**
-
-- `Docs/Backend-Development.md`
-
----
-
 ## [MEDIUM] No CORS configuration
 
 **Where found**