fix(webhook): treat HTTP 409 (rebuild already running) as success, not error

The pmtiles-webhook returns 409 when a rebuild is already in progress.
Previously this was treated as a failure, showing 'Webhook PMTiles
indisponibil' error to the user. Now 409 is handled as a valid state
with appropriate messaging.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/app/(modules)/monitor/page.tsx

@@ -161,13 +161,15 @@ export default function MonitorPage() {
         headers: { "Content-Type": "application/json" },
         body: JSON.stringify({ action: "rebuild" }),
       });
-      const result = await res.json() as { ok?: boolean; error?: string; previousPmtiles?: { lastModified: string }; webhookStatus?: number };
+      const result = await res.json() as { ok?: boolean; error?: string; alreadyRunning?: boolean; previousPmtiles?: { lastModified: string } };
       if (!result.ok) {
         addLog("error", result.error ?? "Eroare necunoscuta");
         setActionLoading("");
         return;
       }
-      addLog("ok", `Webhook trimis (HTTP ${result.webhookStatus}). Rebuild in curs...`);
+      addLog("ok", result.alreadyRunning
+        ? "Rebuild deja in curs. Se monitorizeaza..."
+        : "Webhook trimis. Rebuild pornit...");
       rebuildPrevRef.current = result.previousPmtiles?.lastModified ?? null;
       // Poll every 15s to check if PMTiles was updated
       if (pollRef.current) clearInterval(pollRef.current);