feat(01-02): create MemberNoteController and routes

- MemberNoteController with index() and store() methods
- StoreNoteRequest with Traditional Chinese validation messages
- Routes registered at admin.members.notes.index/store
- JSON responses for AJAX consumption in Phase 2
- DB::transaction wrapper with AuditLogger::log

app/Http/Controllers/Admin/MemberNoteController.php

@@ -0,0 +1,48 @@
+<?php
+
+namespace App\Http\Controllers\Admin;
+
+use App\Http\Controllers\Controller;
+use App\Http\Requests\StoreNoteRequest;
+use App\Models\Member;
+use App\Support\AuditLogger;
+use Illuminate\Support\Facades\DB;
+
+class MemberNoteController extends Controller
+{
+    /**
+     * Get all notes for a member
+     */
+    public function index(Member $member)
+    {
+        $notes = $member->notes()->with('author')->get();
+
+        return response()->json(['notes' => $notes]);
+    }
+
+    /**
+     * Store a new note for a member
+     */
+    public function store(StoreNoteRequest $request, Member $member)
+    {
+        $note = DB::transaction(function () use ($request, $member) {
+            $note = $member->notes()->create([
+                'content' => $request->content,
+                'author_user_id' => $request->user()->id,
+            ]);
+
+            AuditLogger::log('note.created', $note, [
+                'member_id' => $member->id,
+                'member_name' => $member->full_name,
+                'author' => $request->user()->name,
+            ]);
+
+            return $note;
+        });
+
+        return response()->json([
+            'note' => $note->load('author'),
+            'message' => '備忘錄已新增',
+        ], 201);
+    }
+}