Add economic calendar feature with n8n integration

- Add economic calendar tab with monthly view
- Display today's events in header
- Add weekly summary section
- Integrate with Forex Factory via n8n webhook
- Add Header Auth API authentication
- Add KST timezone conversion
- Add country filter (US, JP, CN)
- Add importance-based event styling
- Add more events modal for days with many events
- Update calendar grid to show up to 4 events per day
- Add n8n workflow configuration files

data/economic-calendar.json

@@ -0,0 +1,132 @@
+[
+  {
+    "date": "2025-12-31",
+    "time": "09:00",
+    "country": "CN",
+    "name": "제조업 PMI",
+    "importance": 3,
+    "forecast": "50.2",
+    "previous": "50.3",
+    "actual": null
+  },
+  {
+    "date": "2025-12-31",
+    "time": "23:00",
+    "country": "US",
+    "name": "CB 소비자신뢰지수",
+    "importance": 3,
+    "forecast": "112.0",
+    "previous": "111.7",
+    "actual": null
+  },
+  {
+    "date": "2026-01-01",
+    "time": "08:30",
+    "country": "JP",
+    "name": "실업률",
+    "importance": 2,
+    "forecast": "2.5%",
+    "previous": "2.5%",
+    "actual": null
+  },
+  {
+    "date": "2026-01-01",
+    "time": "10:00",
+    "country": "KR",
+    "name": "산업생산 (MoM)",
+    "importance": 2,
+    "forecast": "0.3%",
+    "previous": "-0.3%",
+    "actual": null
+  },
+  {
+    "date": "2026-01-02",
+    "time": "22:00",
+    "country": "US",
+    "name": "ISM 제조업 PMI",
+    "importance": 3,
+    "forecast": "48.0",
+    "previous": "46.7",
+    "actual": null
+  },
+  {
+    "date": "2026-01-03",
+    "time": "04:00",
+    "country": "US",
+    "name": "FOMC 회의록",
+    "importance": 3,
+    "forecast": "-",
+    "previous": "-",
+    "actual": null
+  },
+  {
+    "date": "2026-01-03",
+    "time": "09:30",
+    "country": "CN",
+    "name": "Caixin 서비스업 PMI",
+    "importance": 2,
+    "forecast": "51.5",
+    "previous": "51.5",
+    "actual": null
+  },
+  {
+    "date": "2026-01-04",
+    "time": "22:30",
+    "country": "US",
+    "name": "비농업 고용지수 (NFP)",
+    "importance": 3,
+    "forecast": "180K",
+    "previous": "227K",
+    "actual": null
+  },
+  {
+    "date": "2026-01-05",
+    "time": "08:00",
+    "country": "KR",
+    "name": "CPI (YoY)",
+    "importance": 3,
+    "forecast": "1.8%",
+    "previous": "1.5%",
+    "actual": null
+  },
+  {
+    "date": "2026-01-06",
+    "time": "10:30",
+    "country": "JP",
+    "name": "경상수지",
+    "importance": 2,
+    "forecast": "2.5T",
+    "previous": "2.3T",
+    "actual": null
+  },
+  {
+    "date": "2026-01-10",
+    "time": "09:00",
+    "country": "KR",
+    "name": "한국은행 기준금리",
+    "importance": 3,
+    "forecast": "3.00%",
+    "previous": "3.00%",
+    "actual": null
+  },
+  {
+    "date": "2026-01-15",
+    "time": "04:00",
+    "country": "US",
+    "name": "FOMC 금리 결정",
+    "importance": 3,
+    "forecast": "4.50%",
+    "previous": "4.50%",
+    "actual": null
+  },
+  {
+    "date": "2026-01-20",
+    "time": "22:30",
+    "country": "US",
+    "name": "GDP (QoQ)",
+    "importance": 3,
+    "forecast": "2.5%",
+    "previous": "2.8%",
+    "actual": null
+  }
+]