fix: surface silent scraper failures and stop falsely claiming weather delay

The homepage was flagging every park as weather delay because calendar.ts
collapsed "fetchLiveRides returned null" into the same openRides=0 bucket as
"all rides actually closed." Meanwhile every scraper (queuetimes, sixflags
operating-hours, sixflags wait-times) was swallowing non-OK responses and
exceptions silently, so logs gave no signal which upstream was failing or how.

Add a small scraperWarn helper that emits in the same shape as backend/log.ts
(without importing it — lib/scrapers is shared with the Next frontend). Use it
in all three scrapers to record HTTP status and error name+message before each
return null. Add parksSkipped to the tier-5 summary log so we can tell when the
openParks filter is rejecting everyone vs the fetcher silently failing.

Convert calendar.ts ridesCache to a discriminated union { kind: "ok" | "unknown" }.
Weather delay only fires on { kind: "ok", openRides: 0 }; unknown entries get
a 30s TTL so we recover quickly when upstream comes back and don't thunder-herd
in the meantime.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

lib/scrapers/sixflags.ts

@@ -7,6 +7,8 @@
  * Rate limiting: on 429/503, exponential backoff (30s → 60s → 120s), MAX_RETRIES attempts.
  */
 
+import { scraperWarn } from "./log";
+
 const API_BASE = "https://d18car1k0ff81h.cloudfront.net/operating-hours/park";
 const MAX_RETRIES = 3;
 const BASE_BACKOFF_MS = 30_000;
@@ -191,9 +193,18 @@ export async function fetchToday(apiId: number, revalidate?: number): Promise<Da
   try {
     const url = `${API_BASE}/${apiId}`;
     const raw = await fetchApi(url, 0, 0, revalidate);
-    if (!raw.dates.length) return null;
+    if (!raw.dates.length) {
+      scraperWarn("sixflags", "fetchToday empty dates array", { apiId });
+      return null;
+    }
     return parseApiDay(raw.dates[0]);
-  } catch {
+  } catch (err) {
+    const e = err as Error;
+    scraperWarn("sixflags", "fetchToday threw", {
+      apiId,
+      name: e.name,
+      err: e.message,
+    });
     return null;
   }
 }
@@ -224,11 +235,22 @@ export async function scrapeRidesForDay(
   let raw: ApiResponse;
   try {
     raw = await scrapeMonthRaw(apiId, year, month, revalidate);
-  } catch {
+  } catch (err) {
+    const e = err as Error;
+    scraperWarn("sixflags", "scrapeRidesForDay scrapeMonthRaw threw", {
+      apiId,
+      year,
+      month,
+      name: e.name,
+      err: e.message,
+    });
     return null;
   }
 
-  if (!raw.dates.length) return null;
+  if (!raw.dates.length) {
+    scraperWarn("sixflags", "scrapeRidesForDay empty dates array", { apiId, year, month });
+    return null;
+  }
 
   // The API uses "MM/DD/YYYY" internally.
   const [, mm, dd] = dateIso.split("-");
@@ -260,8 +282,15 @@ export async function scrapeRidesForDay(
         const nextRaw = await scrapeMonthRaw(apiId, nextYear, nextMonth, revalidate);
         const nextSorted = [...nextRaw.dates].sort((a, b) => a.date.localeCompare(b.date));
         dayData = nextSorted.find((d) => !d.isParkClosed) ?? nextSorted[0];
-      } catch {
-        // If the next month fetch fails, we simply have no fallback data.
+      } catch (err) {
+        const e = err as Error;
+        scraperWarn("sixflags", "scrapeRidesForDay next-month fallback threw", {
+          apiId,
+          year: nextYear,
+          month: nextMonth,
+          name: e.name,
+          err: e.message,
+        });
       }
     }