Add a minimal HTML UI to the Go URL shortener from the beginning of the product experience.\n\nDepends on #26, #27, and #28.\n\nScope:\n- Add signup and login pages.\n- Add an authenticated URL management page.\n- Add forms for creating short URLs and optional custom codes.\n- Display the user's URL list.\n- Keep the UI simple, server-rendered, and local-first.\n- Add handler/template tests where practical.
Add a minimal HTML UI to the Go URL shortener from the beginning of the product experience.\n\nDepends on #26, #27, and #28.\n\nScope:\n- Add signup and login pages.\n- Add an authenticated URL management page.\n- Add forms for creating short URLs and optional custom codes.\n- Display the user's URL list.\n- Keep the UI simple, server-rendered, and local-first.\n- Add handler/template tests where practical.