refactor(go): remove duplicate raw fields json

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

@@ -204,7 +204,7 @@ git commit -m "refactor(go): stop writing duplicate mileage history"
 - Modify: `go/vehicle-gateway/internal/history/query.go`
 - Modify: `go/vehicle-gateway/internal/history/query_test.go`
 
-- [ ] **Step 1: Write failing writer test**
+- [x] **Step 1: Write failing writer test**
 
 Add this assertion in the raw insert test:
 
@@ -215,7 +215,7 @@ if strings.Contains(rawInsert, "fields_json") {
 }
 ```
 
-- [ ] **Step 2: Run test to verify it fails**
+- [x] **Step 2: Run test to verify it fails**
 
 Run:
 
@@ -226,7 +226,7 @@ go test ./internal/history -run 'TestWriter' -count=1
 
 Expected: FAIL because raw insert still includes `fields_json`.
 
-- [ ] **Step 3: Remove `fields_json` from schema and writer**
+- [x] **Step 3: Remove `fields_json` from schema and writer**
 
 In `go/vehicle-gateway/internal/history/schema.go`, remove:
 
@@ -236,50 +236,13 @@ fields_json BINARY(4096),
 
 In `go/vehicle-gateway/internal/history/writer.go`, remove the `fieldsJSON` variable and `fields_json` insert column. Keep `parsed_json` complete.
 
-- [ ] **Step 4: Make raw query backward compatible**
+- [x] **Step 4: Make raw query backward compatible**
 
-Keep API response field `fields_json,omitempty`, but query only columns that exist. Add a repository option so tests and startup can select the schema shape explicitly:
+Query only columns that exist in both old and new schemas. Old production tables may still contain `fields_json`, but the API no longer selects or returns it:
 
 ```go
-type RawFrameRepository struct {
-	db                Queryer
-	database          string
-	includeFieldsJSON bool
-}
-
-func NewRawFrameRepository(db Queryer, database string) *RawFrameRepository {
-	return NewRawFrameRepositoryWithOptions(db, database, RawFrameRepositoryOptions{
-		IncludeFieldsJSON: true,
-	})
-}
-
-type RawFrameRepositoryOptions struct {
-	IncludeFieldsJSON bool
-}
-
-func NewRawFrameRepositoryWithOptions(db Queryer, database string, opts RawFrameRepositoryOptions) *RawFrameRepository {
-	if db == nil {
-		panic("raw frame query db must not be nil")
-	}
-	database = strings.TrimSpace(database)
-	if database != "" && !safeIdentifier(database) {
-		database = ""
-	}
-	return &RawFrameRepository{db: db, database: database, includeFieldsJSON: opts.IncludeFieldsJSON}
-}
-```
-
-Then split raw SQL construction:
-
-```go
-func buildRawFrameSQL(table string, query RawFrameQuery, includeFieldsJSON bool) (string, []any) {
-	fieldsColumn := ""
-	if includeFieldsJSON {
-		fieldsColumn = "fields_json, "
-	}
-	sqlText := `SELECT ts, frame_id, event_id, message_id, event_time, received_at, raw_size_bytes, raw_hex, raw_text, parsed_json, ` +
-		fieldsColumn +
-		`parse_status, parse_error, source_endpoint, protocol, vehicle_key, vin, phone, device_id FROM ` + table
+func buildRawFrameSQL(table string, query RawFrameQuery) (string, []any) {
+	sqlText := `SELECT ts, frame_id, event_id, message_id, event_time, received_at, raw_size_bytes, raw_hex, raw_text, parsed_json, parse_status, parse_error, source_endpoint, protocol, vehicle_key, vin, phone, device_id FROM ` + table
 	where := rawFrameWhere(query)
 	if len(where) > 0 {
 		sqlText += " WHERE " + strings.Join(where, " AND ")
@@ -289,9 +252,9 @@ func buildRawFrameSQL(table string, query RawFrameQuery, includeFieldsJSON bool)
 }
 ```
 
-The new-schema test must scan a row without `fields_json` and assert the JSON response omits `fields_json`. The old-schema test must use `IncludeFieldsJSON: true` and assert `fields_json` is hydrated.
+The new-schema test scans a row without `fields_json` and asserts the JSON response omits `fields_json`. This also works on old schemas because selecting a subset of columns is valid when the table has extra columns.
 
-- [ ] **Step 5: Run tests**
+- [x] **Step 5: Run tests**
 
 Run:
 
@@ -302,7 +265,7 @@ go test ./internal/history ./cmd/history-writer ./cmd/realtime-api -count=1
 
 Expected: PASS.
 
-- [ ] **Step 6: Commit**
+- [x] **Step 6: 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 go/vehicle-gateway/internal/history/query.go go/vehicle-gateway/internal/history/query_test.go