Fix Guestline + Mews direct scrapers after engine API changes

Both competitor booking engines changed their API contracts, silently
breaking their direct scrapes ~16 days ago (200 responses with empty
bodies, so no exception was ever raised):

- Guestline: the /enhanced availability endpoint now returns a bare []
  for every date. Switch to the base /api/availabilities/{coll}/{hotel}
  endpoint, which returns {"rooms":[...]} with the same room shape.
- Mews: getAvailability now rejects the old body with "Invalid
  EnterpriseId" — it requires enterpriseId + serviceId. getPricing
  additionally requires currencyCode. Capture the enterprise's
  defaultCurrencyCode in _ensure_config and send all three.

Also stop last_scraped_at advancing when a run saves 0 rows, so the
overview no longer reports a phantom-fresh scrape while the per-date
data stays stale — the symptom that surfaced this.

Verified live: Three Ways now yields 41 rows/night, Old Stocks 10.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

backend/services/direct_profiles/mews.py

@@ -58,7 +58,11 @@ async def _ensure_config(client, params: dict) -> bool:
     if not enterprise_id:
         enterprise_id = (data.get("enterprises") or [{}])[0].get("id", "")
 
-    tz_name = (data.get("enterprises") or [{}])[0].get("ianaTimeZoneIdentifier", "Europe/London")
+    enterprises = data.get("enterprises") or []
+    ent_obj = next((e for e in enterprises if e.get("id") == enterprise_id),
+                   enterprises[0] if enterprises else {})
+    tz_name = ent_obj.get("ianaTimeZoneIdentifier", "Europe/London")
+    currency = ent_obj.get("defaultCurrencyCode") or "GBP"
 
     # Adult age category: classification=="Adult" or no maximalAge, filtered to this service
     age_cat_id = ""
@@ -72,6 +76,7 @@ async def _ensure_config(client, params: dict) -> bool:
     params["enterprise_id"] = enterprise_id
     params["service_id"] = service_id
     params["age_category_id"] = age_cat_id
+    params["currency"] = currency
     params["_tz"] = ZoneInfo(tz_name)
     return bool(enterprise_id and service_id)
 
@@ -134,6 +139,8 @@ class MewsProfile(BaseProfile):
             f"{API_BASE}/services/getAvailability",
             json={
                 "bookingEngineId": params["booking_engine_id"],
+                "enterpriseId": params["enterprise_id"],
+                "serviceId": params["service_id"],
                 "startUtc": _midnight_utc(today, tz),
                 "endUtc": _midnight_utc(today + timedelta(days=DAYS_AHEAD), tz),
                 "client": CLIENT,
@@ -169,6 +176,9 @@ class MewsProfile(BaseProfile):
             f"{API_BASE}/services/getPricing",
             json={
                 "configurationId": params["booking_engine_id"],
+                "enterpriseId": params["enterprise_id"],
+                "serviceId": params["service_id"],
+                "currencyCode": params.get("currency", "GBP"),
                 "startUtc": _midnight_utc(arrival_date, tz),
                 "endUtc": _midnight_utc(arrival_date + timedelta(days=nights), tz),
                 "occupancyData": [{"ageCategoryId": age_cat_id, "personCount": 2}],