feat: persist map tile settings (provider/style/API keys) server-side on user record; unbake Thunderforest default key into backend config (THUNDERFOREST_DEFAULT_KEY) served via profile

backend/app/main.py

@@ -118,6 +118,15 @@ async def init_db():
     except Exception as e:
         print(f"users.dashboard_layout column migration skipped: {e}")
 
+    # map_settings column on users added after initial creation
+    try:
+        async with engine.begin() as conn:
+            await conn.execute(text(
+                "ALTER TABLE users ADD COLUMN IF NOT EXISTS map_settings JSON"
+            ))
+    except Exception as e:
+        print(f"users.map_settings column migration skipped: {e}")
+
     # Backfill avg_hr_day / max_hr_day from intraday_hr for Garmin Connect synced days
     try:
         async with engine.begin() as conn: