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/paper-extract.ts

@@ -0,0 +1,16 @@
+import { Scenario } from '../types';
+
+export const scenario: Scenario = {
+  id: 'paper-extract',
+  name: 'Paper extract (optional)',
+  description: 'Extract and ingest a PDF (requires network).',
+  tools: ['paperExtract'],
+  enabled: false,
+  notes: 'Enable when network is available; can be slow.',
+  input: {
+    message: 'Add this paper: https://arxiv.org/pdf/1706.03762.pdf',
+  },
+  expect: {
+    toolsCalledSoft: ['paperExtract'],
+  },
+};