Add KiCad PCBnew WASM test infrastructure

- Add pcbnew-load.spec.ts: Tests for WASM runtime initialization
- Add pcbnew.html: Test harness for loading KiCad in browser
- Add setup-kicad-wasm.sh: Script to copy WASM from Docker build
- Add serve.json: COOP/COEP headers for SharedArrayBuffer support
- Update package.json: Add npm run test:kicad and setup:kicad scripts
- Update .gitignore: Exclude generated WASM/JS files from kicad/

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

tests/playwright.config.ts

@@ -72,7 +72,7 @@ export default defineConfig({
   ],
 
   webServer: {
-    command: `npx serve wasm-app -p ${port}`,
+    command: `npx serve wasm-app -p ${port} -c ../serve.json`,
     port: port,
     reuseExistingServer: !process.env.CI,
   },