feat: Add train pre-arrival broadcast via CRN create_target

CloudServer/server.js

@@ -1687,6 +1687,9 @@ function handleMessage(ws, data) {
         case 'train_arrival':
             handleTrainArrival(ws, data);
             break;
+        case 'train_approaching':
+            handleTrainApproaching(ws, data);
+            break;
         case 'train_departure':
             handleTrainDeparture(ws, data);
             break;
@@ -1854,6 +1857,53 @@ function findStationByFlexibleName(targetName) {
     return null;
 }
 
+function handleTrainApproaching(ws, data) {
+    const trainId = data.trainId;
+    const stationName = getCorrectStationName(data.stationName);
+    const stationCode = data.stationCode;
+    const platform = data.stationPlatform || data.platform || '1';
+    
+    const destCode = data.destCode || getStationCodeFromName(data.destination) || 'UNK';
+
+    log('INFO', `Train ${trainId} approaching ${stationName}. Broadcasting pre-arrival...`);
+
+    ws.send(JSON.stringify({
+        type: 'train_approaching_ack',
+        success: true,
+        message: 'Train approaching processed successfully',
+        trainId
+    }));
+
+    // Pre-arrival Audio Logic
+    // 提示音：ksts
+    // 日文：ja-fc1 + ja-站台编号 + ja-fc2 + ja-终点编号 + ja-fc3
+    // 中文：ch-fc1 + ch-fc2 + ch-fc3 + ch-终点编号 + ch-fc4
+    const seq = [
+        'ksts',
+        'ja-fc1', `ja-${platform}`, 'ja-fc2', `ja-${destCode}`, 'ja-fc3',
+        'ch-fc1', 'ch-fc2', 'ch-fc3', `ch-${destCode}`, 'ch-fc4'
+    ];
+    
+    enqueueHlsPush(stationName, seq);
+    
+    const audioId = `approaching-${stationCode}-${Date.now()}`;
+    const built = buildSequenceWavFile(seq);
+    if (built) {
+        enqueueStationAudioTask(stationName, ws, {
+            audioFormat: built.audioFormat,
+            sourcePath: built.sourcePath,
+            streamUrl: built.streamUrl,
+            durationSec: built.durationSec,
+            priority: 1,
+            interruptMode: 'ifLower',
+            source: 'train_approaching',
+            audioId,
+            consoleStreamStart: { type: 'stream_start', station: stationName, seq, streamName: getStationStreamName(stationName), hlsUrl: getStationHlsUrl(getStationStreamName(stationName)) },
+            consoleStreamEnd: { type: 'stream_end', station: stationName }
+        });
+    }
+}
+
 function handleTrainArrival(ws, data) {
     const trainId = data.trainId;
     const stationName = getCorrectStationName(data.stationName);