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.

.gitignore

@@ -1,4 +1,5 @@
 *-PROGRESS.md
+pr-comments*.json
 
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 # Edit at https://www.toptal.com/developers/gitignore?templates=node,nextjs,react