Fix comprehensive lint and type errors across codebase

- Replace explicit 'any' types with 'unknown' or specific types
- Fix Jest DOM test setup with proper type definitions
- Resolve NODE_ENV assignment errors using Object.defineProperty
- Fix React Hook dependency warnings with useCallback patterns
- Remove unused variables and add appropriate ESLint disables
- Update documentation with groups feature information
- Ensure all tests pass with proper TypeScript compliance

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

lib/apiHelpers.ts

@@ -140,7 +140,7 @@ export async function parseRequestBody<T>(
     }
     
     return { success: true, data: body as T };
-  } catch (error) {
+  } catch (_error) {
     return {
       success: false,
       response: createErrorResponse(