feat(wds): live status banner, auto-poll, and instant error emails

- Auto-poll every 15s when sync is running, 60s when idle
- Live status banner: running (with city/step), error list, weekend window waiting, connection error
- Highlight active city card and currently-running step with pulse animation
- Send immediate error email per failed step (not just at session end)
- Expose syncStatus/currentActivity/inWeekendWindow in API response
- Stop silently swallowing fetch/action errors — show them in the UI

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

src/app/api/eterra/weekend-sync/route.ts

@@ -1,8 +1,14 @@
 import { NextResponse } from "next/server";
 import { PrismaClient, Prisma } from "@prisma/client";
+import {
+  isWeekendWindow,
+  getWeekendSyncActivity,
+} from "@/modules/parcel-sync/services/weekend-deep-sync";
 
 const prisma = new PrismaClient();
 
+const g = globalThis as { __parcelSyncRunning?: boolean };
+
 const KV_NAMESPACE = "parcel-sync-weekend";
 const KV_KEY = "queue-state";
 
@@ -116,8 +122,25 @@ export async function GET() {
     dbStats: statsMap.get(c.siruta) ?? { terenuri: 0, cladiri: 0, total: 0, enriched: 0 },
   }));
 
+  // Determine live sync status
+  const running = !!g.__parcelSyncRunning;
+  const activity = getWeekendSyncActivity();
+  const inWindow = isWeekendWindow();
+  const hasErrors = state.cities.some((c) =>
+    (Object.values(c.steps) as StepStatus[]).some((s) => s === "error"),
+  );
+
+  type SyncStatus = "running" | "error" | "waiting" | "idle";
+  let syncStatus: SyncStatus = "idle";
+  if (running) syncStatus = "running";
+  else if (hasErrors) syncStatus = "error";
+  else if (inWindow) syncStatus = "waiting";
+
   return NextResponse.json({
     state: { ...state, cities: citiesWithStats },
+    syncStatus,
+    currentActivity: activity,
+    inWeekendWindow: inWindow,
   });
 }