Implement token-bucket throttler

[SorraTheOrc]

Add src/github-throttler.ts implementing a token-bucket rate limiter with configurable rate (WL_GITHUB_RATE), burst (WL_GITHUB_BURST), and optional concurrency cap (WL_GITHUB_CONCURRENCY). Provide an API to schedule tasks (e.g., schedule(fn): Promise) and to wrap GitHub call helpers. Make the clock injectable to allow deterministic unit tests.\n\nAcceptance criteria:\n- src/github-throttler.ts exists and exports a usable throttler instance and types.\n- Defaults: WL_GITHUB_CONCURRENCY=6, WL_GITHUB_RATE=6, WL_GITHUB_BURST=12 applied when env not set.\n- Unit tests cover refill, burst, depletion, and concurrency cap using an injectable clock.\n

[SorraTheOrc]

OpenCode

Implemented TokenBucketThrottler in src/github-throttler.ts and added unit tests at test/throttler.test.ts. Verified behavior locally: unit tests for refill, burst, depletion, and concurrency cap pass with the injectable FakeClock. No code changes required beyond these files. Ran full test suite locally; file-lock and other timing-sensitive tests also passed. No commit was made in this session.\n\nFiles of interest:\n- src/github-throttler.ts\n- test/throttler.test.ts\n\nNext steps: create a branch and open a PR if you want me to commit and push these changes. Recommend reviewing defaults and optionally adding integration usage where callers should call .

[SorraTheOrc]

OpenCode

Completed work: implemented TokenBucketThrottler and unit tests. PR #918 merged (merge commit 8557484). Changes are on main.