/claim #7528

Summary

When deploying Docker Compose files via GitHub App (dockercompose buildpack), database services were detected but no ServiceDatabase records were created, making automated backups unavailable.

Changes

• Migration: add nullable application_id FK to service_databases, make service_id nullable
• ServiceDatabase model: add application() relationship, update team scopes and helper methods
• Application model: add serviceDatabases() relationship
• parseDockerComposeFile(): create ServiceDatabase records in Application path when database image detected

Closes #7528