feat: enhance security, performance, and stability

This commit introduces a range of improvements across the application:

- **Security:**
  - Adds authentication to the CSP metrics endpoint.
  - Hardens CSP bypass detection regex to prevent ReDoS attacks.
  - Improves CORS headers for the CSP metrics API.
  - Adds filtering for acknowledged alerts in security monitoring.

- **Performance:**
  - Optimizes database connection pooling for NeonDB.
  - Improves session fetching with abort controller.

- **Stability:**
  - Adds error handling to the tRPC demo component.
  - Fixes type inconsistencies in session data mapping.

- **Docs & DX:**
  - Ignores  files in git.
  - Fixes a token placeholder in the documentation.

app/api/admin/security-monitoring/alerts/route.ts

@@ -45,10 +45,18 @@ export async function GET(request: NextRequest) {
     const context = await createAuditContext(request, session);
 
     // Get alerts based on filters
-    const alerts = securityMonitoring.getActiveAlerts(
+    let alerts = securityMonitoring.getActiveAlerts(
       query.severity as AlertSeverity
     );
 
+    // Apply acknowledged filter if provided
+    if (query.acknowledged !== undefined) {
+      const showAcknowledged = query.acknowledged === "true";
+      alerts = alerts.filter((alert) =>
+        showAcknowledged ? alert.acknowledged : !alert.acknowledged
+      );
+    }
+
     // Apply pagination
     const limit = query.limit || 50;
     const offset = query.offset || 0;