Add semantic search and analytics tools for sessions

Phase 7 complete: Advanced session analysis capabilities

New MCP Tools (3):
1. session_semantic_search - Vector similarity search across all sessions
2. session_productivity_analytics - Metrics (avg duration, tasks, commits, tokens)
3. session_pattern_detection - Detect patterns (tool usage, task types)

Features:
- Semantic search with embedding-based similarity
- Fallback to ILIKE text search if embeddings unavailable
- Analytics over configurable time periods (week/month/quarter)
- Pattern detection with frequency analysis

Use Cases:
- Find similar past work: "sessions about WhatsApp integration"
- Track productivity: avg commits/tasks per session
- Identify tool usage patterns: which tools used most often
- Analyze task type distribution

All 7 phases complete! System ready for testing.

Related: CF-257

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

src/tools/index.ts

@@ -939,4 +939,39 @@ export const toolDefinitions = [
       required: ['session_id'],
     },
   },
+  {
+    name: 'session_semantic_search',
+    description: 'Semantic search across all session documentation using vector similarity',
+    inputSchema: {
+      type: 'object',
+      properties: {
+        query: { type: 'string', description: 'Search query' },
+        project: { type: 'string', description: 'Filter by project (optional)' },
+        limit: { type: 'number', description: 'Max results (default: 10)' },
+      },
+      required: ['query'],
+    },
+  },
+  {
+    name: 'session_productivity_analytics',
+    description: 'Get productivity metrics (avg duration, tasks/commits per session, etc.)',
+    inputSchema: {
+      type: 'object',
+      properties: {
+        project: { type: 'string', description: 'Filter by project (optional)' },
+        time_period: { type: 'string', enum: ['week', 'month', 'quarter'], description: 'Time period (default: month)' },
+      },
+    },
+  },
+  {
+    name: 'session_pattern_detection',
+    description: 'Detect patterns across sessions (tool usage, task types)',
+    inputSchema: {
+      type: 'object',
+      properties: {
+        project: { type: 'string', description: 'Filter by project (optional)' },
+        pattern_type: { type: 'string', enum: ['tool_usage', 'task_types', 'error_frequency'], description: 'Type of pattern to detect (default: tool_usage)' },
+      },
+    },
+  },
 ];