fix: install Playwright browsers from lockfile-pinned version in CI

bunx (even with --bun) always downloads a fresh playwright package from
npm, ignoring node_modules/.bin/. This caused a version mismatch:
browsers were downloaded for the latest Playwright (chromium v1208) but
@playwright/test@1.57.0 from the lockfile expected chromium v1200.

Switch to npx which checks node_modules/.bin/ first and invokes the
locally-installed playwright binary, respecting the lockfile pin.

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

Author: pRizz

.github/workflows/ci.yml

@@ -341,8 +341,10 @@ jobs:
           restore-keys: ${{ runner.os }}-playwright-
 
       - name: Install Playwright browsers
-        working-directory: packages/opencode/packages/app
-        run: bunx playwright install --with-deps
+        working-directory: packages/opencode
+        run: |
+          bun install --frozen-lockfile --ignore-scripts
+          npx playwright install --with-deps
         env:
           PLAYWRIGHT_BROWSERS_PATH: ${{ github.workspace }}/.cache/ms-playwright