sync: bug fixes + eval system from private repo

- Fix chunk_status: pass chunk_status/chunk/metadata to context builder
- Fix vector search: scope by node_id BEFORE similarity search
- Add eval logging system (RAH_EVALS_LOG=1)
- Add eval dashboard at /evals
- Add vitest for testing

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

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

tests/evals/scenarios/youtube-extract.ts

@@ -0,0 +1,16 @@
+import { Scenario } from '../types';
+
+export const scenario: Scenario = {
+  id: 'youtube-extract',
+  name: 'YouTube extract (optional)',
+  description: 'Extract and ingest a YouTube video (requires network + API keys).',
+  tools: ['youtubeExtract'],
+  enabled: false,
+  notes: 'Enable when network + API keys are configured; can be flaky.',
+  input: {
+    message: 'Add this video: https://www.youtube.com/watch?v=dQw4w9WgXcQ',
+  },
+  expect: {
+    toolsCalledSoft: ['youtubeExtract'],
+  },
+};