feat: API-Runtime 版本兼容协议 (API-AI-072)

- pollJobs: 记录/更新 RuntimeInstance (capabilities + heartbeat)
- submitResult: 校验 schemaVersion 匹配 job.outputSchemaVersion
- heartbeat: 首次调用设置 startedAt
- 错误码: RESULT_SCHEMA_UNSUPPORTED + RUNTIME_VERSION_INCOMPATIBLE

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/modules/ai-runtime/internal/runtime-internal.service.ts

@@ -35,6 +35,24 @@ export class RuntimeInternalService {
       },
     });
 
+    // Register / update RuntimeInstance with capabilities
+    if (supSnapshot.length > 0 || supOutput.length > 0) {
+      await this.prisma.runtimeInstance.upsert({
+        where: { runtimeInstanceId },
+        create: {
+          runtimeInstanceId,
+          status: 'active',
+          lastHeartbeatAt: new Date(),
+          capabilities: capabilities as any,
+        },
+        update: {
+          status: 'active',
+          lastHeartbeatAt: new Date(),
+          capabilities: capabilities as any,
+        },
+      });
+    }
+
     // Post-filter by snapshotVersion if needed (requires snapshot join)
     if (supSnapshot.length > 0) {
       const snapshotIds = [...new Set(jobs.map(j => j.snapshotId).filter(Boolean))];
@@ -92,14 +110,14 @@ export class RuntimeInternalService {
     const now = new Date();
     const lockUntil = new Date(now.getTime() + 60_000);
 
-    // First heartbeat: locked → running; subsequent heartbeats: extend lockUntil
+    // First heartbeat: locked → running + set startedAt; subsequent: extend lockUntil
     const result = await this.prisma.aiRuntimeJob.updateMany({
       where: {
         id: jobId,
         lockedBy: runtimeInstanceId,
         status: { in: ['locked', 'running'] },
       },
-      data: { lockUntil, status: 'running' },
+      data: { lockUntil, status: 'running', startedAt: new Date() },
     });
 
     if (result.count === 0) {
@@ -176,6 +194,14 @@ export class RuntimeInternalService {
       throw new ConflictException({ errorCode: 'JOB_NOT_ACTIVE', message: `Job is ${job.status}, cannot accept result` });
     }
 
+    // Validate schema version compatibility
+    if (job.outputSchemaVersion && dto.schemaVersion !== job.outputSchemaVersion) {
+      throw new BadRequestException({
+        errorCode: 'RESULT_SCHEMA_UNSUPPORTED',
+        message: `Result schemaVersion ${dto.schemaVersion} does not match job outputSchemaVersion ${job.outputSchemaVersion}`,
+      });
+    }
+
     const resultIdempotencyKey = `${jobId}:${dto.attemptNo}:${dto.outputHash ?? ''}`;
 
     // Check duplicate