improvement: authentication synchronization between terminal and browser

Description

1. While running the supercode login command, the CLI prompted me with a Y/N question asking whether to open the browser automatically.
2. Before responding to the prompt, I manually copied the authentication URL and completed the authorization flow in the browser.
3. After returning to the terminal, there was no synchronization between the web app and the CLI.
4. I then selected No, after which the TUI started polling for the authorization response and continued polling indefinitely.

Expected Behavior

If the user completes the authorization flow manually before responding to the Y/N prompt, the CLI should first check whether the user has already been authenticated.

Suggested flow:

1. Perform a direct database/auth state check to see if authorization has already been completed.
2. If authorization is not found, start polling for the authentication response.

This would prevent unnecessary polling and ensure that manual authorization flows are handled correctly.

Screenshots:

Start at the supercode login command and trace the Y/N prompt and TUI polling path. Inspect how the CLI reads authorization state, then reproduce the manual-browser-before-prompt sequence; done means an already-completed authorization is detected before polling, while incomplete authorization still follows the existing polling flow.