fix: Add missing process.exit(0) calls in hook entry points

All 4 hook entry point scripts were missing process.exit(0) after successful
execution, causing Node processes to hang indefinitely instead of returning
control to Claude Code with exit code 0.

Root cause: In commit 6f62a56, process.exit(0) calls were removed from the
hook functions but were never added to the entry point scripts that wrap them.

Fixed files:
- src/bin/hooks/save-hook.ts (PostToolUse)
- src/bin/hooks/new-hook.ts (UserPromptSubmit)
- src/bin/hooks/summary-hook.ts (Stop)
- src/bin/hooks/context-hook.ts (SessionStart)

This restores proper hook exit behavior and prevents Claude Code from waiting
indefinitely for hook completion.

src/bin/hooks/context-hook.ts

@@ -16,6 +16,7 @@ try {
     stdin.on('end', () => {
       const parsed = input.trim() ? JSON.parse(input) : undefined;
       contextHook(parsed);
+      process.exit(0);
     });
   }
 } catch (error: any) {