feat: wire all 4 obsidian_rag tools to OpenClaw via AnyAgentTool factory

- Replace TypeBox + AgentToolResult with native OpenClaw AnyAgentTool pattern
- Add id, openclaw, main fields to openclaw.plugin.json manifest
- registerTools() now uses factory helpers returning typed AnyAgentTool objects
- toAgentResult() adapter bridges search/index/status/memory results to AgentToolResult shape
- Build clean — pi-agent-core peer dep not needed, openclaw exports all types
- Task list updated: Phase 4 tools + plugin registration marked complete

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

openclaw.plugin.json

@@ -1,9 +1,12 @@
 {
   "schema_version": "1.0",
+  "id": "obsidian-rag",
   "name": "obsidian-rag",
   "version": "0.1.0",
   "description": "Semantic search through Obsidian vault notes using RAG. Powers natural language queries like 'How was my mental health in 2024?' across journal entries, financial records, health data, and more.",
   "author": "Santhosh Janardhanan",
+  "openclaw": "^2026.4.9",
+  "main": "dist/index.js",
   "tools": [
     {
       "name": "obsidian_rag_search",