feat: store jt808 daily mileage as metric

docs/superpowers/plans/2026-06-30-kafka-streaming-mileage.md

@@ -10,7 +10,8 @@ Consume JT808 Kafka location events, keep rolling daily state, and write the der
 - Runtime app: `vehicle-analytics-app`
 - State: Redis or in-memory `Jt808MileageStateStore`
 - Metric output: `VehicleStatRepository.saveDailyStat(...)`
-- Default metric storage: `VEHICLE_STAT_FILE_PATH/daily-stats.tsv`
+- Production metric storage: JDBC/MySQL `vehicle_stat_metric`
+- Local fallback storage: `VEHICLE_STAT_FILE_PATH/daily-stats.tsv`
 - Date boundary: `Asia/Shanghai`
 
 JT808 daily mileage is calculated only from the GPS total mileage reported by JT808 location additional information:
@@ -27,8 +28,11 @@ The stream saves a metric only when at least two ordered location points for the
 KAFKA_TOPIC_JT808_EVENT=vehicle.event.jt808.v1
 VEHICLE_STAT_ENABLED=true
 VEHICLE_STAT_JT808_MILEAGE_ENABLED=true
+VEHICLE_STAT_REPOSITORY_TYPE=jdbc
 VEHICLE_STAT_JT808_STATE_STORE=redis
-VEHICLE_STAT_FILE_PATH=/data/vehicle-stat
+MYSQL_JDBC_URL=<jdbc-url>
+MYSQL_USERNAME=<user>
+MYSQL_PASSWORD=<password>
 REDIS_HOST=<host>
 REDIS_PORT=6379
 REDIS_DATABASE=50