Remove raw git:// protocol (port 9418) and expose HTTP smart protocol on port 5000

[juliuskrah]

Summary

The git-service currently exposes port 9418 labelled as "Git protocol" in the Compose configuration. The raw git:// protocol is unauthenticated, unencrypted, and should not be used in any deployment that approaches production. The service already speaks HTTP smart protocol; this task migrates that binding to port 5000 and removes the legacy port 9418 declaration.

Scope

In Scope:

• Change GITSTORE_GIT_PORT from 9418 to 5000 in compose.yml and any environment defaults.
• Update the ports mapping in the git-service service to expose 5000 instead of 9418.
• Remove or gate the raw git:// protocol listener in gitstore-git-service source code; only HTTP smart protocol should be served.
• Update the service healthcheck to probe port 5000.
• Update any inter-service references (e.g. GITSTORE_GIT_WS, git clone URLs in scripts and docs) to use the new port.
• Update docs/user-guide.md clone examples from http://localhost:9418/catalog.git to http://localhost:5000/catalog.git.
• Verify git clone, git fetch, and git push all work over HTTP smart protocol on port 5000.

Out of scope:

• Implementing smart http protocol
• Implementing ssh protocol
• Implementing authentication

Acceptance Criteria

• Port 9418 is no longer exposed on any GitStore Compose service.
• git clone http://localhost:5000/catalog.git succeeds end-to-end.
• No git:// scheme is used anywhere in compose files, scripts, or documentation.
• Healthchecks pass on the updated port.