Add comprehensive backend features and mobile UI improvements

Backend:
- Add 2FA authentication with TOTP support
- Add API keys management system
- Add audit logging for security events
- Add file upload/management system
- Add notifications system with preferences
- Add session management
- Add webhooks integration
- Add analytics endpoints
- Add export functionality
- Add password policy enforcement
- Add new database migrations for core tables

Frontend:
- Add module position system (top/bottom sidebar sections)
- Add search and notifications module configuration tabs
- Add mobile logo replacing hamburger menu
- Center page title absolutely when no tabs present
- Align sidebar footer toggles with navigation items
- Add lighter icon color in dark theme for mobile
- Add API keys management page
- Add notifications page with context
- Add admin analytics and audit logs pages

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/app/main.py

@@ -8,6 +8,9 @@ from fastapi import FastAPI, Request
 from fastapi.middleware.cors import CORSMiddleware
 from fastapi.responses import JSONResponse, FileResponse
 from fastapi.staticfiles import StaticFiles
+from slowapi import Limiter, _rate_limit_exceeded_handler
+from slowapi.util import get_remote_address
+from slowapi.errors import RateLimitExceeded
 import logging
 import time
 
@@ -17,6 +20,12 @@ from app.api.v1 import router as api_v1_router
 from app.db.session import engine
 from app.db.base import Base
 
+# Import all models so they're registered with Base.metadata before create_all
+from app.models import (  # noqa: F401
+    User, Settings, AuditLog, APIKey, Notification,
+    UserSession, Webhook, WebhookDelivery, StoredFile
+)
+
 # Static files path
 STATIC_DIR = Path(__file__).parent.parent / "static"
 
@@ -29,6 +38,10 @@ logging.basicConfig(
 logger = logging.getLogger(__name__)
 
 
+# Rate limiter setup
+limiter = Limiter(key_func=get_remote_address, default_limits=["200/minute"])
+
+
 # Create FastAPI application
 app = FastAPI(
     title=settings.APP_NAME,
@@ -39,6 +52,10 @@ app = FastAPI(
     openapi_url=f"{settings.API_V1_PREFIX}/openapi.json"
 )
 
+# Add rate limiter to app state
+app.state.limiter = limiter
+app.add_exception_handler(RateLimitExceeded, _rate_limit_exceeded_handler)
+
 
 # CORS middleware
 app.add_middleware(