fix: refresh live goal sidebar counters

[danyel117]

Closes #62.

Summary

• Refresh the OpenCode 1 and 2 goal sidebars from the shared, atomically written goal state file so token usage, auto-continue counts, and checkpoints update during long runs.
• Keep transcript snapshots as the fallback when the state file is unavailable; distinguish a cleared goal from a failed read.
• Share the lightweight state-path resolver between the server and source-shipped TUI, and include it in the published package.

Validation

• bun run lint — passed.
• bun run typecheck — passed.
• bun test — 314 passed, 0 failed.
• bun run build — passed.
• bun run pack:dry-run — passed; includes src/state-path.ts and the TUI source.

Claude Opus audit

• Audit 1: found a high-severity stale-sidebar case after clear and a medium test gap; both fixed.
• Audit 2: found the same stale-counter behavior in the OpenCode 1 sidebar; fixed with shared polling and a regression test.
• Audit 3: found a medium test timing risk; switched test state writes to atomic rename and extended deadlines. No fourth audit was requested. No known high or medium findings remain.