The waitForEventProcessorShutdown test was comparing exact string match
against console.log spy, but picocolors wraps the message in ANSI dim
codes. On CI (bun 1.3.9) this caused the assertion to fail. Use
string containment check instead of exact argument match.
Add unit tests for resolveRunAgent() covering:
- CLI flag takes priority over env and config
- Env var takes priority over config
- Config takes priority over default
- Falls back to sisyphus when none set
- Skips disabled agent and picks next available core agent