refactor(go): stop duplicate mileage history writes

docs/superpowers/plans/2026-07-02-storage-simplification.md

@@ -37,7 +37,7 @@
 - Modify: `go/vehicle-gateway/internal/history/query.go`
 - Modify: `go/vehicle-gateway/internal/history/query_test.go`
 
-- [ ] **Step 1: Write the failing test**
+- [x] **Step 1: Write the failing test**
 
 Update `TestMileagePointHandlerReturnsMileageByVehicleKey` in `go/vehicle-gateway/internal/history/query_test.go` so it expects `vehicle_locations`, not `vehicle_mileage_points`:
 
@@ -51,7 +51,7 @@ mock.ExpectQuery("SELECT ts, event_id, frame_id, received_at, total_mileage_km,
 	}).AddRow("2026-07-02 10:00:00.000", "event-1", "frame-1", "2026-07-02 10:00:01.000", 8792.8, 8.0, 121.07764, 31.22436, "JT808", "JT808:13307811350", "VIN001", "13307811350", "dev001"))
 ```
 
-- [ ] **Step 2: Run test to verify it fails**
+- [x] **Step 2: Run test to verify it fails**
 
 Run:
 
@@ -62,7 +62,7 @@ go test ./internal/history -run 'TestMileagePointHandlerReturnsMileageByVehicleK
 
 Expected: FAIL because `MileagePointRepository.tableName()` still returns `vehicle_mileage_points`.
 
-- [ ] **Step 3: Point mileage repository at location table**
+- [x] **Step 3: Point mileage repository at location table**
 
 Change `MileagePointRepository.tableName()` in `go/vehicle-gateway/internal/history/query.go`:
 
@@ -108,7 +108,7 @@ func mileagePointWhere(query MileagePointQuery) []string {
 }
 ```
 
-- [ ] **Step 4: Run tests**
+- [x] **Step 4: Run tests**
 
 Run:
 
@@ -119,7 +119,7 @@ go test ./internal/history -count=1
 
 Expected: PASS.
 
-- [ ] **Step 5: Commit**
+- [x] **Step 5: Commit**
 
 ```bash
 git add go/vehicle-gateway/internal/history/query.go go/vehicle-gateway/internal/history/query_test.go
@@ -133,7 +133,7 @@ git commit -m "refactor(go): read mileage points from locations"
 - Modify: `go/vehicle-gateway/internal/history/writer.go`
 - Modify: `go/vehicle-gateway/internal/history/writer_test.go`
 
-- [ ] **Step 1: Write the failing tests**
+- [x] **Step 1: Write the failing tests**
 
 Update `go/vehicle-gateway/internal/history/writer_test.go`:
 
@@ -151,7 +151,7 @@ if got := countSQL(exec.calls, "INSERT INTO mil_"); got != 0 {
 }
 ```
 
-- [ ] **Step 2: Run test to verify it fails**
+- [x] **Step 2: Run test to verify it fails**
 
 Run:
 
@@ -162,7 +162,7 @@ go test ./internal/history -run 'TestWriter' -count=1
 
 Expected: FAIL because schema and writer still create/write `vehicle_mileage_points`.
 
-- [ ] **Step 3: Remove duplicate write path**
+- [x] **Step 3: Remove duplicate write path**
 
 Change `AppendAll` in `go/vehicle-gateway/internal/history/writer.go`:
 
@@ -177,7 +177,7 @@ func (w *Writer) AppendAll(ctx context.Context, env envelope.FrameEnvelope) erro
 
 Remove `vehicle_mileage_points` from `SchemaStatements` in `go/vehicle-gateway/internal/history/schema.go`. Keep `AppendMileagePoint` only if tests still use it directly; otherwise remove the function and its helper after compile errors guide cleanup.
 
-- [ ] **Step 4: Run tests**
+- [x] **Step 4: Run tests**
 
 Run:
 
@@ -188,7 +188,7 @@ go test ./internal/history ./cmd/history-writer -count=1
 
 Expected: PASS.
 
-- [ ] **Step 5: Commit**
+- [x] **Step 5: Commit**
 
 ```bash
 git add go/vehicle-gateway/internal/history/schema.go go/vehicle-gateway/internal/history/writer.go go/vehicle-gateway/internal/history/writer_test.go