feat(db): device_readings 新增 metric 字段用于多行拆分存储

crates/erp-server/migration/src/lib.rs

@@ -91,6 +91,7 @@ mod m20260428_000088_rls_policy_strict;
 mod m20260428_000089_blind_indexes;
 mod m20260428_000090_critical_alerts;
 mod m20260428_000091_dead_letter_events;
+mod m20260429_000092_device_readings_metric;
 
 pub struct Migrator;
 
@@ -189,6 +190,7 @@ impl MigratorTrait for Migrator {
             Box::new(m20260428_000089_blind_indexes::Migration),
             Box::new(m20260428_000090_critical_alerts::Migration),
             Box::new(m20260428_000091_dead_letter_events::Migration),
+            Box::new(m20260429_000092_device_readings_metric::Migration),
         ]
     }
 }