feat: Session persistence with Redis + Draft management fixes

- Implement session management API (/api/v1/session/create, verify, logout)
- Add session restoration from localStorage on page reload
- Fix session_id priority when loading drafts (use current, not old from DB)
- Add unified_id and claim_id to wizard payload sent to n8n
- Add Docker volume for frontend HMR (Hot Module Replacement)
- Add comprehensive session logging for debugging

Components updated:
- backend/app/api/session.py (NEW) - Session management endpoints
- backend/app/main.py - Include session router
- frontend/src/components/form/Step1Phone.tsx v2.0 - Create session after SMS
- frontend/src/pages/ClaimForm.tsx v3.8 - Session restoration & priority fix
- frontend/src/components/form/StepWizardPlan.tsx v1.4 - Add unified_id/claim_id
- docker-compose.yml - Add frontend volume for live reload

Session flow:
1. User verifies phone -> session created in Redis (24h TTL)
2. session_token saved to localStorage
3. Page reload -> session restored automatically
4. Draft selected -> current session_id used (not old from DB)
5. Wizard submit -> unified_id, claim_id, session_id sent to n8n
6. Logout -> session removed from Redis & localStorage

Fixes:
- Session token not persisting after page reload
- unified_id missing in n8n webhook payload
- Old session_id from draft overwriting current session
- Frontend changes requiring container rebuild

frontend/src/components/DebugPanel.tsx

@@ -52,9 +52,9 @@ export default function DebugPanel({ events, formData }: Props) {
         }}
         styles={{
           header: {
-            background: '#252526',
-            color: '#fff',
-            borderBottom: '1px solid #333'
+          background: '#252526',
+          color: '#fff',
+          borderBottom: '1px solid #333'
           },
           body: {
             padding: 12