fix: resolve oxlint errors across codebase (#24)

## Summary
- Remove 5 unused `beforeEach` imports from test files
- Remove unused imports (`existsSync`, `TimelineCompositionElement`)
- Remove unused destructured variables (`options`, `width`, `height`, `goldenEl`)
- Remove dead `formatDuration` function
- Fix unused catch parameters (`catch (err)` → `catch`)
- Prefix unused `renderError` state with `_`
- Add `eslint-disable-next-line` for 2 React exhaustive-deps false positives (stable ref + zustand setter)

Part 2/4 of [VA-851](https://linear.app/heygen/issue/VA-851/pre-migration-configure-eslint-prettier-and-conventional-commits)

## Test plan
- [x] `pnpm lint` — 0 errors on 193 files
- [x] All 348 tests pass (core + engine)

packages/engine/src/services/frameCapture.ts

@@ -121,7 +121,7 @@ export async function createCaptureSession(
 }
 
 export async function initializeSession(session: CaptureSession): Promise<void> {
-  const { page, serverUrl, options } = session;
+  const { page, serverUrl } = session;
 
   // Forward browser console to host with [Browser] prefix
   page.on("console", (msg: ConsoleMessage) => {