test(perf): track-only runtime-perf E2E for eeschema + pcbnew

Measures the current build's cold load, open+render, and pan/zoom FPS
(1x/4x/6x CPU-throttle sweep) for both editors, writing
tests/test-results/perf-*.json. Track-only: asserts only that the app booted
and the document opened — no perf thresholds, so it never gates CI.

Runs on a new Chromium `perf` Playwright project (CDP throttling; pcbnew needs
V8 anyway) via `npm run test:perf`, and is wired into wasm-build.yml as a
continue-on-error step so the numbers are captured/uploaded without flaking the
gate. Reuses the existing fixtures, ready-signal, fs-inject, and board-ready
helpers; FPS counter is cancel-able so a throttle sweep on one page doesn't
accumulate rAF loops.

.gitignore: ignore /benchmark-builds/ (disposable prebuilt-WASM + standalone
harness bundle used to reproduce the native-vs-JS-EH comparison locally).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.github/workflows/wasm-build.yml

@@ -304,6 +304,16 @@ jobs:
         working-directory: tests
         run: xvfb-run -a npm run test:kicad:ci
 
+      # Runtime-perf E2E (eeschema + pcbnew): measures the current build's
+      # load / open+render / FPS and writes tests/test-results/perf-*.json.
+      # Track-only — never gates the build (continue-on-error). CI is
+      # headless/SwiftShader so FPS is CPU-bound + noisy; openMs is the stable number.
+      - name: KiCad runtime perf (track-only, non-gating)
+        if: inputs.run_tests
+        continue-on-error: true
+        working-directory: tests
+        run: xvfb-run -a npm run test:perf
+
       - name: Upload test logs & screenshots
         if: always() && inputs.run_tests
         uses: actions/upload-artifact@v4