v0.13.0 app-server fallback build

Fork build of the Codex Rate Limit Monitor with the app-server fallback fix and related diagnostics improvements.

Highlights:

reads live rate limits from local session token_count data when available
falls back to the local codex app-server when newer session events omit rate_limits
falls back again to the latest session snapshot with rate_limits if needed
adds clearer source visibility in the UI and structured output log levels
fix bundled Codex binary lookup for app-server fallback

This fork build corresponds to PR xiangz19#3 against the upstream repository.
All code, documentation, and packaging changes were created with AI assistance.