feat: Implement Phase 1 of SDK agent architecture with hook integration

- Added CLI commands for context, new session, save observation, and summary.
- Created HooksDatabase for managing SDK sessions and observations.
- Implemented migration 004 to add new tables: sdk_sessions, observation_queue, observations, and session_summaries.
- Developed hook functions for context display, session initialization, observation queuing, and session finalization.
- Added comprehensive tests for database schema and hook functionality.
- Documented Phase 1 implementation in PHASE1-COMPLETE.md.

src/hooks/summary.ts

@@ -0,0 +1,50 @@
+import { HooksDatabase } from '../services/sqlite/HooksDatabase.js';
+
+export interface StopInput {
+  session_id: string;
+  cwd: string;
+  [key: string]: any;
+}
+
+/**
+ * Summary Hook - Stop
+ * Signals SDK to finalize and generate summary
+ */
+export function summaryHook(input: StopInput): void {
+  try {
+    const { session_id } = input;
+
+    // Find active SDK session
+    const db = new HooksDatabase();
+    const session = db.findActiveSDKSession(session_id);
+
+    if (!session) {
+      // No active session - nothing to finalize
+      db.close();
+      console.log('{"continue": true, "suppressOutput": true}');
+      process.exit(0);
+    }
+
+    // Insert special FINALIZE message into observation queue
+    const sdkSessionId = session.sdk_session_id || `pending-${session.id}`;
+
+    db.queueObservation(
+      sdkSessionId,
+      'FINALIZE',
+      '{}',
+      '{}'
+    );
+
+    db.close();
+
+    // Output hook response
+    console.log('{"continue": true, "suppressOutput": true}');
+    process.exit(0);
+
+  } catch (error: any) {
+    // On error, don't block Claude Code
+    console.error(`[claude-mem summary error: ${error.message}]`);
+    console.log('{"continue": true, "suppressOutput": true}');
+    process.exit(0);
+  }
+}