measure: track DORA metrics for v0.4.0 post-release

[paruff]

DORA Measurement Request

Triggered by release agent after v0.4.0 release (2026-07-08).

Metrics to compute

1. Deployment Frequency: How many releases in the last 30 days?
2. Lead Time for Changes: Median time from first commit to release tag.
3. Change Failure Rate: How many hotfixes or rollbacks since last measurement?
4. Time to Restore Service: Mean time to resolve CI failures.

Scope

• Repo: paruff/prei
• Period: 2026-06-08 to 2026-07-08
• Tag range: v0.3.1-alpha.2 to v0.4.0

Deliverable

Brief DORA snapshot report in this issue.