fix: prevent infinite message replay on container timeout (#164)

Container timeout and idle timeout both fire at 30min, racing the
graceful shutdown. The hard kill returns error status, rolling back
the message cursor even though output was already sent — causing
duplicate messages indefinitely.

- Grace period: hard timeout is now IDLE_TIMEOUT + 30s minimum
- Timeout after output resolves as success (idle cleanup, not failure)
- Don't roll back cursor if output was already sent to user
- Remove src/telegram.ts and config vars (added to PR #156 by mistake)
- Add typecheck step to CI workflow
- Add container-runner timeout behavior tests

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.github/workflows/test.yml

@@ -14,4 +14,5 @@ jobs:
           node-version: 20
           cache: npm
       - run: npm ci
+      - run: npx tsc --noEmit
       - run: npx vitest run