Add standalone hook entry points for context, new, save, summary, and worker

- Implemented context-hook.ts for handling session start events.
- Created new-hook.ts for user prompt submission events.
- Developed save-hook.ts for post tool use events.
- Added summary-hook.ts for handling stop events.
- Introduced worker.ts as a standalone background process for the SDK agent.
- Each hook reads input from stdin, processes it, and handles errors gracefully.

src/bin/hooks/summary-hook.ts

@@ -0,0 +1,20 @@
+#!/usr/bin/env bun
+
+/**
+ * Summary Hook Entry Point - Stop
+ * Standalone executable for plugin hooks
+ */
+
+import { summaryHook } from '../../hooks/summary.js';
+
+// Read input from stdin
+const input = await Bun.stdin.text();
+
+try {
+  const parsed = input.trim() ? JSON.parse(input) : undefined;
+  summaryHook(parsed);
+} catch (error: any) {
+  console.error(`[claude-mem summary-hook error: ${error.message}]`);
+  console.log('{"continue": true, "suppressOutput": true}');
+  process.exit(0);
+}