perf: split monolithic E2E test into 8 parallel files

Split test/skill-e2e.test.ts (3442 lines) into 8 category files:
- skill-e2e-browse.test.ts (7 tests)
- skill-e2e-review.test.ts (7 tests)
- skill-e2e-qa-bugs.test.ts (3 tests)
- skill-e2e-qa-workflow.test.ts (4 tests)
- skill-e2e-plan.test.ts (6 tests)
- skill-e2e-design.test.ts (7 tests)
- skill-e2e-workflow.test.ts (6 tests)
- skill-e2e-deploy.test.ts (4 tests)

Bun runs each file in its own worker = 10 parallel workers
(8 split + routing + codex). Expected: 78 min → ~12 min.

Extracted shared helpers to test/helpers/e2e-helpers.ts.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

test/touchfiles.test.ts

@@ -191,14 +191,17 @@ describe('detectBaseBranch', () => {
   });
 });
 
-// --- Completeness: every testName in skill-e2e.test.ts has a TOUCHFILES entry ---
+// --- Completeness: every testName in skill-e2e-*.test.ts has a TOUCHFILES entry ---
 
 describe('TOUCHFILES completeness', () => {
   test('every E2E testName has a TOUCHFILES entry', () => {
-    const e2eContent = fs.readFileSync(
-      path.join(ROOT, 'test', 'skill-e2e.test.ts'),
-      'utf-8',
-    );
+    // Read all split E2E test files
+    const testDir = path.join(ROOT, 'test');
+    const e2eFiles = fs.readdirSync(testDir).filter(f => f.startsWith('skill-e2e-') && f.endsWith('.test.ts'));
+    let e2eContent = '';
+    for (const f of e2eFiles) {
+      e2eContent += fs.readFileSync(path.join(testDir, f), 'utf-8') + '\n';
+    }
 
     // Extract all testName: 'value' entries
     const testNameRegex = /testName:\s*['"`]([^'"`]+)['"`]/g;