feat: environment model + deployment tracking (phase 3a)

- Environment/Deployment XORM models + migration 010
- Full CRUD API: GET/POST/PATCH/DELETE /environments + /deployments
- Deployment status update endpoint, publishes deployment.* NATS events
- EnvironmentsPage with deploy cards, history accordion, deploy modal
- Sidebar Environments nav item between Pipelines and Settings
- Repo page deployment status badges (env name + SHA pill per
  environment)
- Environment/Deployment types in types/api.ts + environments.ts query
  hooks

internal/models/migrations/001_init.go

@@ -37,5 +37,8 @@ func Run(engine *xorm.Engine) error {
 	if err := Run008(engine); err != nil {
 		return err
 	}
-	return Run009(engine)
+	if err := Run009(engine); err != nil {
+		return err
+	}
+	return Run010(engine)
 }