Use registry-backed server image in production packages

[den-sq]

Goal

Use the published GHCR server image for production app startup instead of building the Python server image from bundled source on first launch.

Context

PR #86 publishes:

• ghcr.io/chenglabresearch/ouroboros-server:<release-tag>
• ghcr.io/chenglabresearch/ouroboros-server:sha-<commit>

Production startup currently loads extra-resources/server/compose.yml from src/main/servers/main-server.ts. The bundled production compose file should reference a release image instead of using build:.

Scope

• Generate or package extra-resources/server/compose.yml with an immutable image: reference for the current release.
• Preserve the current ports, volume, extra_hosts, environment, and shm_size behavior.
• Keep a local-build fallback for development or emergency use, but do not make production startup build by default.
• Document how release tags map to GHCR image tags.
• Verify a production app package starts the main server by pulling the image instead of building it.

Acceptance Criteria

• A production package includes a server compose file using ghcr.io/chenglabresearch/ouroboros-server:<release-tag> or a digest-pinned equivalent.
• First launch pulls the server image and does not run a Docker build for the core server.
• Development compose files still build from source.
• Release documentation identifies the image tag/digest used by the package.

[den-sq]

Feeds the production release flavor matrix in #87.

This issue should land before the package flavors are finalized, because all three packages need the registry-backed core server compose path.

[tavateva]

Time Estimate: 2-3 hours

Breakdown:

• Compose file generation/templating: ~1h
• Production startup integration: ~1h
• Verification (build vs pull behavior): ~0.5h
• Documentation: ~0.5h

Complexity factors:

• Straightforward image reference swap (build → image)
• Must preserve existing ports/volumes/environment behavior
• Compose file generation may need build-time or release-workflow integration

Dependencies:

• PR [codex] Publish registry-backed server images #86 must be merged (provides the GHCR server images)
• No blocking dependencies from other issues

[den-sq]

Closed by #90,