Add /version endpoint returning build version and git commit

[kltm]

Problem

There is no way to programmatically determine which version of the API is running on a given instance. This makes it difficult to verify deployments, especially when the production instance is behind Cloudflare and its origin IP cannot be resolved via DNS.

Proposed solution

Add a /version or /health endpoint that returns:

• The Docker image tag / release version (e.g. 0.3.9-a)
• The git commit SHA the image was built from

This would allow automated verification that the correct code is deployed after a release, and help identify which instance Cloudflare is pointing to without needing to check the Cloudflare dashboard manually.