Add processor heartbeat management and improve health check functionality

- Introduced processor heartbeat configuration in environment variables and Docker setup.
- Implemented heartbeat publishing in the processor worker.
- Enhanced health check endpoint to include processor availability status.
- Updated frontend components to handle processor unavailability messages.
- Added legacy return functionality in the upload panel.

faceai/apps/processor/src/worker.js

@@ -10,6 +10,7 @@ import {
   markSearchFailed,
   markSearchProcessing,
   releaseActiveSearchLock,
+  updateProcessorHeartbeat,
   storeResultRecord
 } from '../../backend/src/redis-store.js';
 import { parseMatcherCsv, resolvePklPath, runFaceMatcher } from './worker-utils.js';
@@ -34,6 +35,18 @@ async function ensureMatcherBinaryAvailable() {
 
 console.log(`FaceAI processor configured matcher binary: ${config.matcherBinary}`);
 
+async function publishProcessorHeartbeat() {
+  try {
+    await updateProcessorHeartbeat(connection, config.processorHeartbeatTtlSeconds, {
+      pid: process.pid,
+      queueName: config.queueName,
+      matcherBinary: config.matcherBinary
+    });
+  } catch (error) {
+    console.error('Unable to publish FaceAI processor heartbeat:', error);
+  }
+}
+
 function formatLogLine(message, details) {
   const timestamp = new Date().toISOString();
   if (details === undefined) {
@@ -167,6 +180,13 @@ async function processJob(job) {
 }
 
 await ensureMatcherBinaryAvailable();
+await publishProcessorHeartbeat();
+
+const heartbeatTimer = setInterval(() => {
+  publishProcessorHeartbeat();
+}, config.processorHeartbeatIntervalMs);
+
+heartbeatTimer.unref();
 
 const worker = new Worker(config.queueName, processJob, {
   connection,