feat: Trading Economics API for upcoming events with forecasts

- New services/te_calendar.py: fetch_upcoming(weeks_ahead) calls TE API
  for 9 countries (USD/EUR/GBP/JPY/AUD/CAD/NZD/CHF/CNY), converts to
  ff_calendar format, upserts with source='te_api'
- New endpoints: GET/POST /api/eco/te-key, POST /api/eco/te-sync,
  GET /api/eco/te-sync/status
- Daily scheduler in main.py: FF live sync + TE sync (if key configured)
  run 60s after startup then every 24h
- CalendarPage: TEPanel with key input (password field, Enter to save,
  "Get free key" link to tradingeconomics.com/api/login),
  "Sync upcoming (6 weeks)" button with polling

FF HTML scraper kept as fallback but TE API is the primary source
for upcoming forecasts (no Cloudflare blocking on server IPs).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/main.py

@@ -95,21 +95,33 @@ def startup():
     from services.institutional_scheduler import start_institutional_scheduler
     start_institutional_scheduler()
 
-    # Daily FF scraper — runs once at startup, then every 24h
+    # Daily calendars sync — FF live (this week) + TE upcoming (if key configured)
     import threading, time as _time
-    def _ff_scrape_loop():
-        _time.sleep(30)  # let server fully boot first
+    def _daily_calendar_sync():
+        _time.sleep(60)  # let server fully boot first
         while True:
             try:
-                print("[Startup] FF scrape upcoming weeks …", flush=True)
-                from services.ff_calendar import scrape_upcoming
-                result = scrape_upcoming(weeks_ahead=5)
-                print(f"[FF scrape] done: {result.get('total_upserted', 0)} upserted", flush=True)
+                # FF live JSON — this week actuals
+                from services.ff_calendar import sync_live
+                r = sync_live()
+                print(f"[Daily] FF live sync: {r}", flush=True)
             except Exception as e:
-                print(f"[FF scrape] loop error: {e}", flush=True)
-            _time.sleep(86400)  # 24h
+                print(f"[Daily] FF live sync error: {e}", flush=True)
 
-    threading.Thread(target=_ff_scrape_loop, daemon=True).start()
+            try:
+                # Trading Economics — upcoming forecasts (only if key is set)
+                from services.database import get_config
+                te_key = get_config("te_api_key") or ""
+                if te_key:
+                    from services.te_calendar import fetch_upcoming
+                    r = fetch_upcoming(weeks_ahead=6)
+                    print(f"[Daily] TE sync: {r.get('total_upserted', 0)} upserted", flush=True)
+            except Exception as e:
+                print(f"[Daily] TE sync error: {e}", flush=True)
+
+            _time.sleep(86400)  # repeat every 24h
+
+    threading.Thread(target=_daily_calendar_sync, daemon=True).start()
 
     # Auto-import Forex Factory CSV if file is present (force, then delete CSV)
     import threading