fix(ralph-loop): clear orphaned state when original session no longer exists (#446)

* fix(ralph-loop): clear orphaned state when original session no longer exists

When a session with an active ralph-loop terminates abnormally (abort, window close),
the state file remains with active: true. Previously, when a new session started,
the hook would skip the orphaned state without cleaning it up.

This fix adds session existence validation:
- Before skipping a loop owned by a different session, check if that session still exists
- If the original session no longer exists, clear the orphan state and log
- If the original session still exists, skip as before (it's another active session's loop)

Changes:
- Add checkSessionExists option to RalphLoopOptions for dependency injection
- Wire up sessionExists from session-manager as the default implementation
- Add tests for orphan state cleanup and active session preservation

* fix(ralph-loop): add error handling around checkSessionExists call

Wraps the async checkSessionExists call in try/catch for consistency
with other async operations in this file. If the check throws, logs
the error and falls back to the original behavior (not clearing state).

---------

Co-authored-by: sisyphus-dev-ai <sisyphus-dev-ai@users.noreply.github.com>

src/tools/index.ts

@@ -28,6 +28,8 @@ import {
   session_info,
 } from "./session-manager"
 
+export { sessionExists } from "./session-manager/storage"
+
 export { interactive_bash, startBackgroundCheck as startTmuxCheck } from "./interactive-bash"
 export { createSkillTool } from "./skill"
 export { getTmuxPath } from "./interactive-bash/utils"