feat: Enhance project and scenario creation with monitoring metrics

- Added monitoring metrics for project creation success and error handling in `ProjectRepository`.
- Implemented similar monitoring for scenario creation in `ScenarioRepository`.
- Refactored `run_monte_carlo` function in `simulation.py` to include timing and success/error metrics.
- Introduced new CSS styles for headers, alerts, and navigation buttons in `main.css` and `projects.css`.
- Created a new JavaScript file for navigation logic to handle chevron buttons.
- Updated HTML templates to include new navigation buttons and improved styling for buttons.
- Added tests for reporting service and routes to ensure proper functionality and access control.
- Removed unused imports and optimized existing test files for better clarity and performance.

middleware/auth_session.py

@@ -9,6 +9,7 @@ from starlette.types import ASGIApp
 
 from config.settings import Settings, get_settings
 from models import User
+from monitoring.metrics import ACTIVE_CONNECTIONS
 from services.exceptions import EntityNotFoundError
 from services.security import (
     JWTSettings,
@@ -45,6 +46,8 @@ class _ResolutionResult:
 class AuthSessionMiddleware(BaseHTTPMiddleware):
     """Resolve authenticated users from session cookies and refresh tokens."""
 
+    _active_sessions: int = 0
+
     def __init__(
         self,
         app: ASGIApp,
@@ -61,9 +64,23 @@ class AuthSessionMiddleware(BaseHTTPMiddleware):
 
     async def dispatch(self, request: Request, call_next: RequestResponseEndpoint) -> Response:
         resolved = self._resolve_session(request)
-        response = await call_next(request)
-        self._apply_session(response, resolved)
-        return response
+
+        # Track active sessions for authenticated users
+        if resolved.session.user and resolved.session.user.is_active:
+            AuthSessionMiddleware._active_sessions += 1
+            ACTIVE_CONNECTIONS.set(AuthSessionMiddleware._active_sessions)
+
+        try:
+            response = await call_next(request)
+            return response
+        finally:
+            # Decrement on response
+            if resolved.session.user and resolved.session.user.is_active:
+                AuthSessionMiddleware._active_sessions = max(
+                    0, AuthSessionMiddleware._active_sessions - 1)
+                ACTIVE_CONNECTIONS.set(AuthSessionMiddleware._active_sessions)
+
+            self._apply_session(response, resolved)
 
     def _resolve_session(self, request: Request) -> _ResolutionResult:
         settings = self._settings_provider()