Sprint 0-1: Python indexer, TS plugin scaffolding, and test suite

## What's new

**Python indexer (`python/obsidian_rag/`)** — full pipeline from scan to LanceDB:
- `config.py` — JSON config loader with cross-platform path resolution
- `security.py` — path traversal prevention, HTML stripping, sensitive content detection, dir allow/deny lists
- `chunker.py` — section-split for journal entries (date-named files), sliding-window for unstructured notes
- `embedder.py` — Ollama `/api/embeddings` client with batched requests and timeout/error handling
- `vector_store.py` — LanceDB schema, upsert (merge_insert), delete, search with filters, stats
- `indexer.py` — full/sync/reindex pipeline orchestrator with progress yields
- `cli.py` — `index | sync | reindex | status` CLI commands

**TypeScript plugin (`src/`)** — OpenClaw plugin scaffold:
- `utils/` — config loader, TypeScript types, response envelope factory, LanceDB client
- `services/` — health state machine (HEALTHY/DEGRADED/UNAVAILABLE), vault watcher with debounce/batching, indexer bridge (subprocess spawner)
- `tools/` — 4 tool stubs: search, index, status, memory_store (OpenClaw wiring pending)
- `index.ts` — plugin entry point with health probe + vault watcher startup

**Config** (`obsidian-rag/config.json`, `openclaw.plugin.json`):
- 627 files / 3764 chunks indexed in dev vault

**Tests: 76 passing**
- Python: 64 pytest tests (chunker, security, vector_store, config)
- TypeScript: 12 vitest tests (lancedb client, response envelope)

## Bugs fixed

- LanceDB `tags` column filter: `LIKE '%tag%'` → `list_contains(tags, 'tag')` (List<String> column)
- LanceDB JS `db.list_tables()` returns `ListTablesResponse` object, not plain array
- LanceDB JS result score field: `_score` → `_distance`
- TypeScript regex literal with unescaped `/` in path-resolve regex
- Python: `create_table_if_not_exists` identity check → name comparison

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/unit/response.test.ts

@@ -0,0 +1,50 @@
+/** Unit tests for security guard and response envelope utilities in TS. */
+
+import { describe, it, expect } from "vitest";
+import { makeEnvelope, errorEnvelope } from "../../src/utils/response.js";
+
+describe("makeEnvelope", () => {
+  it("creates a healthy envelope with data", () => {
+    const envelope = makeEnvelope<string[]>(
+      "healthy",
+      ["a", "b"],
+      null,
+      { query_time_ms: 42 }
+    );
+    expect(envelope.status).toBe("healthy");
+    expect(envelope.data).toEqual(["a", "b"]);
+    expect(envelope.error).toBeNull();
+    expect(envelope.meta.query_time_ms).toBe(42);
+  });
+
+  it("creates a degraded envelope without data", () => {
+    const envelope = makeEnvelope("degraded", null, null, { chunks_scanned: 0 });
+    expect(envelope.status).toBe("degraded");
+    expect(envelope.data).toBeNull();
+  });
+
+  it("defaults meta fields", () => {
+    const envelope = makeEnvelope("healthy", [], null, {});
+    expect(envelope.meta.index_version).toBe("0.1.0");
+    expect(envelope.meta.vault_mtime).toBeDefined();
+  });
+});
+
+describe("errorEnvelope", () => {
+  it("creates an unavailable error envelope", () => {
+    const envelope = errorEnvelope(
+      "INDEX_NOT_FOUND",
+      "Vector index not found at expected path",
+      false,
+      "Run 'obsidian-rag index' to create the index"
+    );
+    expect(envelope.status).toBe("unavailable");
+    expect(envelope.data).toBeNull();
+    expect(envelope.error).toEqual({
+      code: "INDEX_NOT_FOUND",
+      message: "Vector index not found at expected path",
+      recoverable: false,
+      suggestion: "Run 'obsidian-rag index' to create the index",
+    });
+  });
+});