refactor(db): use version string as primary key for ConfigVersion

-transition `of_config_versions` primary key from `id` to `version` string.
-add database migration files `202606270001_make_version_primary_key.sql` for PostgreSQL and SQLite.
-introduce AfterFind/AfterCreate GORM hooks to preserve JSON backward compatibility.
-refactor API controllers, logics, and front-end typescript definitions to receive `string` parameter.

internal/apps/openflare/flared/observability_test.go

@@ -27,6 +27,7 @@ func setupFlaredObservabilityTestDB(t *testing.T) func() {
 		&model.OpenFlareNode{},
 		&model.OpenFlareHealthEvent{},
 		&model.SystemConfig{},
+		&model.ConfigVersion{},
 	))
 
 	db.SetDB(sqliteDB)