Update all router files to use Echo v5 APIs and type signatures.
Changes in router.go:
- Replace echomiddleware.Logger() with RequestLogger() (line 144)
- Update import from echo/v4 to echo/v5
Changes in frontend.go:
- Update frontend handler signatures to use *echo.Context
- Fix middleware registration for v5 compatibility
Changes in auth.go, library.go, scanner.go, sync.go, helpers.go:
- Update handler function signatures to *echo.Context
- Ensure consistent type usage across all route handlers
All routes now properly implement Echo v5's middleware and handler patterns.