feat(frontend): T47-T54 implement web interface routes

- Add web router with all frontend pages
- Login/Register pages with form validation
- Dashboard with stats cards and Chart.js
- API Keys management with CRUD operations
- Stats page with filtering and pagination
- API Tokens management with generation/revocation
- User profile with password change and account deletion
- Add shared templates_config.py to avoid circular imports
- Add CSRF protection middleware
- Add get_current_user_optional dependency for web routes

All routes verified working:
- GET /login, POST /login
- GET /register, POST /register
- POST /logout
- GET /dashboard
- GET /keys, POST /keys, DELETE /keys/{id}
- GET /stats
- GET /tokens, POST /tokens, DELETE /tokens/{id}
- GET /profile, POST /profile/password, DELETE /profile

src/openrouter_monitor/main.py

@@ -8,15 +8,16 @@ from pathlib import Path
 from fastapi import FastAPI, Request
 from fastapi.middleware.cors import CORSMiddleware
 from fastapi.staticfiles import StaticFiles
-from fastapi.templating import Jinja2Templates
 
 from openrouter_monitor.config import get_settings
+from openrouter_monitor.templates_config import templates
 from openrouter_monitor.middleware.csrf import CSRFMiddleware
 from openrouter_monitor.routers import api_keys
 from openrouter_monitor.routers import auth
 from openrouter_monitor.routers import public_api
 from openrouter_monitor.routers import stats
 from openrouter_monitor.routers import tokens
+from openrouter_monitor.routers import web
 from openrouter_monitor.tasks.scheduler import init_scheduler, shutdown_scheduler
 
 settings = get_settings()
@@ -39,9 +40,6 @@ async def lifespan(app: FastAPI):
 # Get project root directory
 PROJECT_ROOT = Path(__file__).parent.parent.parent
 
-# Configure Jinja2 templates
-templates = Jinja2Templates(directory=str(PROJECT_ROOT / "templates"))
-
 # Create FastAPI app
 app = FastAPI(
     title="OpenRouter API Key Monitor",
@@ -72,6 +70,7 @@ app.include_router(api_keys.router, prefix="/api/keys", tags=["api-keys"])
 app.include_router(tokens.router)
 app.include_router(stats.router)
 app.include_router(public_api.router)
+app.include_router(web.router)
 
 
 @app.get("/")