* fix: add retry logic for transient socket errors
Fixes race condition when rapidly closing and opening browser sessions.
The daemon has a 100ms shutdown delay, which caused the CLI to detect
stale daemons as "running" and fail with EAGAIN errors.
Changes:
- Add retry logic (5 attempts, exponential backoff) for transient errors
including EAGAIN, EOF, connection reset, and connection refused
- Add 150ms verification delay in ensure_daemon to detect shutting-down daemons
- Add cleanup_stale_files to remove leftover socket/PID files before starting
a new daemon
Tested with 20 rapid close/open cycles and 100+ parallel commands.
* test: add unit tests for transient error detection
Extracts is_transient_error() function and adds 14 unit tests covering:
- EAGAIN errors (macOS os error 35, Linux os error 11)
- WouldBlock and Resource temporarily unavailable
- EOF and empty JSON response errors
- Connection reset (macOS os error 54, Linux os error 104)
- Broken pipe errors
- Socket not found (os error 2)
- Connection refused (macOS os error 61, Linux os error 111)
- Non-transient errors (verifies they are NOT retried)
Chris Tate
775f166bce