[Backend Release] v0.50.2

[deploystack-automation]

Backend Release v0.50.2

This PR prepares a new backend release.

When merged, this will:

1. Create a release tag
2. Build and publish a multi-architecture Docker image to Docker Hub

The Docker image will be available at:

• deploystack/backend:latest
• deploystack/backend:v0.50.2

Supported Architectures

• linux/amd64 (Intel/AMD)
• linux/arm64 (Apple Silicon, AWS Graviton)

Release notes:

• fix(backend): clarify backend API base URL description (1f6ef4eb)
• fix(backend): emit USER_REGISTERED event for new GitHub users (8d84726e)
• fix(backend): include drizzle migrations in Docker image (bc4c9aff)
• fix(backend): update run-local-postgres script for consistency (dda8eb9b)
• fix(backend): update MCP installation email templates for clarity (ee9c3bfd)

[deploystack-automation]

Release Branch Cleanup ✅

Branch backend-release has been automatically deleted after PR was merged.