Implement silent update check and installation on launch

[LargeModGames]

This pull request removes the in-app update prompt and background update check, replacing it with an automatic, silent update mechanism that runs at startup. The update logic has been refactored, and all code and UI related to the previous update prompt has been removed, simplifying the user experience and codebase.

Update mechanism changes:

• Introduced a new install_update_silent function in src/cli/update.rs that checks for, downloads, and installs updates automatically, returning the new version if updated. This function is now used in place of the previous update check functions.
• The application now performs an auto-update check on launch (unless a CLI subcommand is used or the SPOTATUI_SKIP_UPDATE environment variable is set). If an update is installed, the app restarts itself automatically.

Removal of update prompt UI and logic:

• Removed all code, UI, and navigation related to the in-app update prompt, including the UpdatePrompt and associated state and handlers in src/core/app.rs, src/tui/handlers/mod.rs, src/tui/ui/popups.rs, and related files.

Refactoring and cleanup:

• Refactored the update module exports and removed unused code, such as the UpdateInfo struct and related functions that are no longer needed.
• Cleaned up startup and event loop logic in src/main.rs to remove all references to the old update prompt and background check.

These changes streamline the update experience for users and reduce code complexity by removing the manual update prompt and related UI.

Testing

• cargo fmt --all
• cargo clippy --locked -- -D warnings
• cargo test --locked

[chatgpt-codex-connector]

You have reached your Codex usage limits for code reviews. You can see your limits in the Codex usage dashboard.