feat: replace Trading Economics with FMP for upcoming calendar forecasts

TE costs $199/month and its Economic Calendar is not in the free tier.
FMP (Financial Modeling Prep) offers a free API key (250 req/day) with
full economic calendar coverage including consensus estimates (forecasts).

- Add backend/services/fmp_calendar.py: fetches upcoming events from
  GET /api/v3/economic_calendar (one request, all countries, date range)
- Replace /api/eco/te-key + te-sync endpoints with fmp-key + fmp-sync
- Update daily background sync in main.py to use fmp_calendar
- Replace TEPanel with FMPPanel in CalendarPage.tsx (link to FMP docs)
- Remove broken Cloudflare-blocked FF HTML scrape button from ImportPanel

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

backend/routers/eco.py

@@ -420,52 +420,52 @@ def ff_scrape_status_ep() -> Dict[str, Any]:
     return _ff_scrape_status
 
 
-# ── Trading Economics calendar (upcoming weeks with forecasts) ─────────────────
+# ── FMP calendar (upcoming weeks with consensus forecasts) ────────────────────
 
-@router.get("/te-key")
-def get_te_key() -> Dict[str, Any]:
-    from services.te_calendar import check_te_key
-    return check_te_key()
+@router.get("/fmp-key")
+def get_fmp_key() -> Dict[str, Any]:
+    from services.fmp_calendar import check_fmp_key
+    return check_fmp_key()
 
 
-@router.post("/te-key")
-def save_te_key(key: str = Query(..., description="Trading Economics API key")) -> Dict[str, Any]:
+@router.post("/fmp-key")
+def save_fmp_key(key: str = Query(..., description="FMP API key")) -> Dict[str, Any]:
     from services.database import set_config
     key = key.strip()
     if not key:
         raise HTTPException(400, "Empty key")
-    set_config("te_api_key", key)
+    set_config("fmp_api_key", key)
     return {"status": "saved", "preview": key[:4] + "…" + key[-4:]}
 
 
-def _run_te_sync(weeks_ahead: int):
+def _run_fmp_sync(weeks_ahead: int):
     global _te_sync_status
     _te_sync_status["running"] = True
     try:
-        from services.te_calendar import fetch_upcoming
+        from services.fmp_calendar import fetch_upcoming
         result = fetch_upcoming(weeks_ahead=weeks_ahead)
         _te_sync_status["last_result"] = result
     except Exception as e:
-        logger.error(f"[eco/te-sync] Failed: {e}")
+        logger.error(f"[eco/fmp-sync] Failed: {e}")
         _te_sync_status["last_result"] = {"error": str(e)}
     finally:
         _te_sync_status["running"] = False
 
 
-@router.post("/te-sync")
-def te_sync(
+@router.post("/fmp-sync")
+def fmp_sync(
     background_tasks: BackgroundTasks,
     weeks: int = Query(6, ge=1, le=12),
 ) -> Dict[str, Any]:
-    """Fetch upcoming economic events + forecasts from Trading Economics API."""
+    """Fetch upcoming economic events + forecasts from FMP API (free, 250 req/day)."""
     if _te_sync_status["running"]:
-        raise HTTPException(409, "TE sync already running")
-    background_tasks.add_task(_run_te_sync, weeks)
+        raise HTTPException(409, "FMP sync already running")
+    background_tasks.add_task(_run_fmp_sync, weeks)
     return {"status": "started", "weeks_ahead": weeks}
 
 
-@router.get("/te-sync/status")
-def te_sync_status_ep() -> Dict[str, Any]:
+@router.get("/fmp-sync/status")
+def fmp_sync_status_ep() -> Dict[str, Any]:
     return _te_sync_status