Add tool documentation MCP tools for queryable TOOLS.md replacement

- Created tool_docs table with pgvector support (migration 015)
- Added 5 MCP tools: tool_doc_add, tool_doc_search, tool_doc_get, tool_doc_list, tool_doc_export
- Imported 268 tools from TOOLS.md to database
- Enables semantic search for tool documentation (when embeddings available)
- Reduces context pollution (TOOLS.md is 11,769 lines, now queryable)

Task: CF-249

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

migrations/015_tool_docs.sql

@@ -0,0 +1,36 @@
+-- Migration 015: Tool Documentation
+-- Creates tool_docs table for queryable tool documentation with semantic search
+-- Dependencies: 001_base_schema.sql (pgvector extension)
+
+-- Tool documentation table
+CREATE TABLE IF NOT EXISTS tool_docs (
+    id SERIAL PRIMARY KEY,
+    tool_name TEXT NOT NULL,
+    category TEXT NOT NULL CHECK (category IN ('mcp', 'cli', 'script', 'internal', 'deprecated')),
+    title TEXT NOT NULL,
+    description TEXT NOT NULL,
+    usage_example TEXT,
+    parameters JSONB,  -- Structured parameter definitions
+    notes TEXT,  -- Additional notes, gotchas, tips
+    tags TEXT[],  -- Searchable tags (e.g., ['backup', 'database', 'postgresql'])
+    source_file TEXT,  -- Original source file (TOOLS.md, script path, etc.)
+    embedding vector(1024),  -- Semantic search embedding
+    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
+    updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW()
+);
+
+-- Indexes for fast lookups
+CREATE INDEX IF NOT EXISTS idx_tool_docs_name ON tool_docs(tool_name);
+CREATE INDEX IF NOT EXISTS idx_tool_docs_category ON tool_docs(category);
+CREATE INDEX IF NOT EXISTS idx_tool_docs_tags ON tool_docs USING gin(tags);
+
+-- HNSW index for semantic similarity search
+CREATE INDEX IF NOT EXISTS idx_tool_docs_embedding ON tool_docs USING hnsw (embedding vector_cosine_ops);
+
+-- Full-text search on title + description
+CREATE INDEX IF NOT EXISTS idx_tool_docs_fts ON tool_docs
+    USING gin(to_tsvector('english', title || ' ' || description || ' ' || COALESCE(notes, '')));
+
+-- Record migration
+INSERT INTO schema_migrations (version) VALUES ('015_tool_docs')
+ON CONFLICT (version) DO NOTHING;