Enhance timestamp on deployment table #5766

Context

Follow-up from the deployment list redesign. Currently the deployment cards show a relative timestamp (e.g. "5m ago") and a GitHub avatar separately.

Proposal

Combine the timestamp and avatar into a single hoverable tooltip interaction:

• The default view shows the relative timestamp and avatar inline (as it does now)
• On hover, show a tooltip that includes the full/absolute timestamp
• Could also surface the GitHub username of the deployer in the tooltip — worth exploring but not a hard requirement

So the end state could be something like:

5min ago by Dave Hawkins

Possibly worth exploring whether the tooltip should include the github author or not too, or whether just the avatar on the main view would suffice.