Align DeliveryResult tags and make the index table test-local

Re-align the json tag column in DeliveryResult after the wider
DeliveryID gorm tag, and move the test's index table out of package
scope into the test function.

Model: opus-5-5

internal/database/event_tier_indexes_test.go

@@ -17,24 +17,24 @@ type indexedColumn struct {
 	field string
 }
 
-// eventTierIndexes are the columns the background work reads by: the
-// recovery and sweep queries (status), the event log (event_id and
-// delivery_id) and retention (created_at).
-var eventTierIndexes = []indexedColumn{
-	{&database.Delivery{}, "Status"},
-	{&database.Delivery{}, "EventID"},
-	{&database.DeliveryResult{}, "DeliveryID"},
-	{&database.Event{}, "CreatedAt"},
-}
-
 // TestWebhookDBManager_OpenAddsEventTierIndexes verifies that opening a
 // per-webhook database that predates these indexes creates them, so the
-// queries above stop scanning whole tables. It stands in for an older
-// database file by dropping the indexes AutoMigrate just created, then
-// reopening the same file.
+// queries that read by those columns stop scanning whole tables. It
+// stands in for an older database file by dropping the indexes
+// AutoMigrate just created, then reopening the same file.
 func TestWebhookDBManager_OpenAddsEventTierIndexes(t *testing.T) {
 	t.Parallel()
 
+	// The columns the background work reads by: the recovery and sweep
+	// queries (status), the event log (event_id and delivery_id) and
+	// retention (created_at).
+	eventTierIndexes := []indexedColumn{
+		{&database.Delivery{}, "Status"},
+		{&database.Delivery{}, "EventID"},
+		{&database.DeliveryResult{}, "DeliveryID"},
+		{&database.Event{}, "CreatedAt"},
+	}
+
 	mgr, lc := setupTestWebhookDBManager(t)
 	ctx := context.Background()
 	require.NoError(t, lc.Start(ctx))

internal/database/model_delivery_result.go

@@ -5,10 +5,10 @@ type DeliveryResult struct {
 	BaseModel
 
 	DeliveryID   string `gorm:"type:uuid;not null;index" json:"deliveryId"`
-	AttemptNum   int    `gorm:"not null"             json:"attemptNum"`
+	AttemptNum   int    `gorm:"not null"                 json:"attemptNum"`
 	Success      bool   `json:"success"`
 	StatusCode   int    `json:"statusCode,omitempty"`
-	ResponseBody string `gorm:"type:text"            json:"responseBody,omitempty"`
+	ResponseBody string `gorm:"type:text"                json:"responseBody,omitempty"`
 	Error        string `json:"error,omitempty"`
 	Duration     int64  `json:"durationMs"` // Duration in milliseconds