Add stamp source hashing and maximize test infrastructure

- Add source hashing to stamp system (functions.sh) for detecting
  when dependencies need rebuild based on source file changes
- Update build-pcbnew.sh to use source stamps for wxWidgets
- Add global-setup.ts to clean logs before test runs
- Add maximize_test standalone test to verify wxFrame::Maximize()
  works correctly in WASM (it does - window is 1280x720)
- Update Makefile.wasm with maximize test build rules

The maximize_test proves wxWidgets display detection works fine.
KiCad's 20x20 window bug is KiCad-specific, not a wxWidgets issue.

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

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

tests/playwright.config.ts

@@ -46,6 +46,7 @@ function findFreePort(): number {
 const port = getOrFindPort();
 
 export default defineConfig({
+  globalSetup: './global-setup.ts',
   testDir: './e2e',
   fullyParallel: true,
   forbidOnly: !!process.env.CI,