refactor: achieve 100% biome compliance with comprehensive code quality improvements

- Fix all cognitive complexity violations (63→0 errors)
- Replace 'any' types with proper TypeScript interfaces and generics
- Extract helper functions and custom hooks to reduce complexity
- Fix React hook dependency arrays and useCallback patterns
- Remove unused imports, variables, and functions
- Implement proper formatting across all files
- Add type safety with interfaces like AIProcessingRequestWithSession
- Fix circuit breaker implementation with proper reset() method
- Resolve all accessibility and form labeling issues
- Clean up mysterious './0' file containing biome output

Total: 63 errors → 0 errors, 42 warnings → 0 warnings

app/api/csrf-token/route.ts

@@ -5,7 +5,6 @@
  * It generates a new token and sets it as an HTTP-only cookie.
  */
 
-import type { NextRequest } from "next/server";
 import { generateCSRFTokenResponse } from "../../../middleware/csrfProtection";
 
 /**