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/api/geoportal/monitor/route.ts

@@ -162,8 +162,8 @@ export async function POST(request: NextRequest) {
   if (action === "rebuild") {
     // Get current PMTiles state before rebuild
     const before = await getPmtilesInfo();
-    const ok = await firePmtilesRebuild("manual-rebuild");
-    if (!ok) {
+    const result = await firePmtilesRebuild("manual-rebuild");
+    if (!result.ok) {
       return NextResponse.json(
         { error: "Webhook PMTiles indisponibil — verifica N8N_WEBHOOK_URL si serviciul pmtiles-webhook" },
         { status: 500 },
@@ -172,8 +172,11 @@ export async function POST(request: NextRequest) {
     return NextResponse.json({
       ok: true,
       action: "rebuild",
+      alreadyRunning: result.alreadyRunning ?? false,
       previousPmtiles: before,
-      message: "Rebuild PMTiles pornit. Dureaza ~8 min. Urmareste PMTiles last-modified.",
+      message: result.alreadyRunning
+        ? "Rebuild PMTiles deja in curs. Urmareste PMTiles last-modified."
+        : "Rebuild PMTiles pornit. Dureaza ~8 min. Urmareste PMTiles last-modified.",
     });
   }