Refactor: Modularize memo.py to 3-layer architecture, Fix tag extraction regex, and Enhance infinite scroll for large screens

app/routes/stats.py

@@ -0,0 +1,12 @@
+from flask import Blueprint, request, jsonify # type: ignore
+from ..auth import login_required
+from ..services.memo_service import MemoService
+
+stats_bp = Blueprint('stats', __name__)
+
+@stats_bp.route('/api/stats/heatmap', methods=['GET'])
+@login_required
+def get_heatmap_stats():
+    days = request.args.get('days', 365, type=int)
+    stats = MemoService.get_heatmap_stats(days)
+    return jsonify(stats)