Clean up test infrastructure and fix test assertions

- Replace test.skip() with proper expect() assertions when app fails to load
- Remove button-finder utility (no longer needed with element registry)
- Remove kicad tests (tested separately)
- Add findByName/clickByName helpers for bitmap buttons
- Fix element lookups: use clickByName for bitmap buttons, clickTreeItem
  for treebook pages, selectComboItem for wxChoice items
- Add SetName() to shape buttons in bitmapbuttons_test.cpp
- Remove verbose logging from print and threadpool tests
- Update README to reflect current test infrastructure

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

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

tests/e2e/printpreview.spec.ts

@@ -17,10 +17,7 @@ test.describe('wxPrintPreview Tests', () => {
   test('Preview area displays schematic-like content', async ({ page, testLogger }) => {
     await page.goto('/standalone/printpreview/printpreview_test.html');
     const loaded = await tryLoadApp(page);
-    if (!loaded) {
-      test.skip();
-      return;
-    }
+    expect(loaded, 'App should load').toBe(true);
 
     await page.waitForTimeout(500);
 
@@ -31,10 +28,7 @@ test.describe('wxPrintPreview Tests', () => {
   test('Print Preview button opens preview frame', async ({ page, testLogger }) => {
     await page.goto('/standalone/printpreview/printpreview_test.html');
     const loaded = await tryLoadApp(page);
-    if (!loaded) {
-      test.skip();
-      return;
-    }
+    expect(loaded, 'App should load').toBe(true);
 
     await page.waitForTimeout(300);
 
@@ -49,10 +43,7 @@ test.describe('wxPrintPreview Tests', () => {
   test('Page Setup button opens dialog', async ({ page, testLogger }) => {
     await page.goto('/standalone/printpreview/printpreview_test.html');
     const loaded = await tryLoadApp(page);
-    if (!loaded) {
-      test.skip();
-      return;
-    }
+    expect(loaded, 'App should load').toBe(true);
 
     await page.waitForTimeout(300);
 
@@ -67,10 +58,7 @@ test.describe('wxPrintPreview Tests', () => {
   test('Print settings display shows current configuration', async ({ page, testLogger }) => {
     await page.goto('/standalone/printpreview/printpreview_test.html');
     const loaded = await tryLoadApp(page);
-    if (!loaded) {
-      test.skip();
-      return;
-    }
+    expect(loaded, 'App should load').toBe(true);
 
     await page.waitForTimeout(500);