feat(backend): Implement enhanced profile management

Phase 2.4 - Enhanced Profile Management

Features implemented:
- Get user profile endpoint
- Update user profile endpoint
- Delete user account endpoint with password confirmation
- Input validation on all profile fields
- Security: Password required for account deletion
- Security: All tokens revoked on deletion

New API endpoints:
- GET /api/users/me (protected)
- PUT /api/users/me (protected)
- DELETE /api/users/me (protected)

Security features:
- JWT token required for all operations
- Password confirmation required for deletion
- All tokens revoked on account deletion
- User data removed from database
- Input validation on all fields

Files modified:
- backend/src/handlers/users.rs
- backend/src/main.rs

Testing:
- backend/test-profile-management.sh
- backend/PROFILE-MANAGEMENT-IMPLEMENTED.md

backend/PROFILE-MANAGEMENT-IMPLEMENTED.md

@@ -0,0 +1,90 @@
+# Enhanced Profile Management - Complete
+
+## Status: ✅ Implementation Complete
+
+**Date**: 2026-02-15 19:32:00 UTC  
+**Feature**: Phase 2.4 - Enhanced Profile Management
+
+---
+
+## API Endpoints
+
+| Endpoint | Method | Auth Required | Description |
+|----------|--------|---------------|-------------|
+| `/api/users/me` | GET | ✅ Yes | Get current user profile |
+| `/api/users/me` | PUT | ✅ Yes | Update user profile |
+| `/api/users/me` | DELETE | ✅ Yes | Delete user account |
+
+---
+
+## Features
+
+### 1. Get User Profile
+```bash
+GET /api/users/me
+Authorization: Bearer <token>
+```
+
+Response:
+```json
+{
+  "id": "...",
+  "email": "user@example.com",
+  "username": "username",
+  "recovery_enabled": true,
+  "email_verified": false,
+  "created_at": "2026-02-15T19:32:00Z",
+  "last_active": "2026-02-15T19:32:00Z"
+}
+```
+
+### 2. Update Profile
+```bash
+PUT /api/users/me
+Authorization: Bearer <token>
+Content-Type: application/json
+
+{
+  "username": "newusername",
+  "full_name": "John Doe",
+  "phone": "+1234567890",
+  "address": "123 Main St",
+  "city": "New York",
+  "country": "USA",
+  "timezone": "America/New_York"
+}
+```
+
+### 3. Delete Account
+```bash
+DELETE /api/users/me
+Authorization: Bearer <token>
+Content-Type: application/json
+
+{
+  "password": "CurrentPassword123!"
+}
+```
+
+Security:
+- ✅ Password required
+- ✅ All tokens revoked
+- ✅ Data removed from database
+
+---
+
+## Testing
+
+Run the test script:
+```bash
+cd backend
+./test-profile-management.sh
+```
+
+---
+
+## Files Modified
+
+- backend/src/handlers/users.rs
+- backend/src/main.rs
+- backend/test-profile-management.sh