fix: only sample wait times within each park's operating window

Queue-Times keeps reporting yesterday's last wait with isOpen=true overnight,
so the per-ride open check wasn't enough — the sampler was recording phantom
"open" samples between close and the next morning's first refresh, padding
both wait-time averages and uptime% with stale data.

Add isWithinOperatingWindow gate (same check the /rides route uses) so the
sampler only runs during the park's actual hours plus the 1-hour closing
buffer. Includes a one-off wipe script for the accumulated bad data.

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

backend/scripts/wipe-samples.ts

@@ -0,0 +1,26 @@
+/**
+ * One-off cleanup: wipe ride history accumulated before the operating-window
+ * gate was added to the sampler. Safe to re-run; truncates only the two
+ * sample-related tables, leaves park_days untouched.
+ */
+import Database from "better-sqlite3";
+import path from "path";
+
+const dbPath = path.join(__dirname, "..", "data", "parks.db");
+const db = new Database(dbPath);
+
+const before = {
+  samples: (db.prepare("SELECT COUNT(*) AS c FROM ride_wait_samples").get() as { c: number }).c,
+  rides: (db.prepare("SELECT COUNT(*) AS c FROM rides").get() as { c: number }).c,
+};
+console.log("Before:", before);
+
+db.exec("DELETE FROM ride_wait_samples; DELETE FROM rides;");
+
+const after = {
+  samples: (db.prepare("SELECT COUNT(*) AS c FROM ride_wait_samples").get() as { c: number }).c,
+  rides: (db.prepare("SELECT COUNT(*) AS c FROM rides").get() as { c: number }).c,
+};
+console.log("After: ", after);
+
+db.close();