feat: hook eval-store sync, use shared utils, add 30 lib tests

- eval-store.ts: import shared getGitInfo/getVersion, add pushEvalRun()
  hook in finalize() (non-blocking, non-fatal)
- session-runner.ts: import shared atomicWriteSync/sanitizeForFilename
- eval-store.test.ts: fix pre-existing bug in double-finalize test
  (was counting _partial file)
- 30 new tests for lib/util, lib/sync-config, lib/sync

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

test/helpers/eval-store.test.ts

@@ -114,7 +114,8 @@ describe('EvalCollector', () => {
 
     expect(filepath1).toBeTruthy();
     expect(filepath2).toBe(''); // second call returns empty
-    expect(fs.readdirSync(tmpDir).filter(f => f.endsWith('.json'))).toHaveLength(1);
+    // Exclude _partial files — savePartial writes _partial-e2e.json alongside the final
+    expect(fs.readdirSync(tmpDir).filter(f => f.endsWith('.json') && !f.startsWith('_partial'))).toHaveLength(1);
   });
 
   test('empty collector writes valid file', async () => {