v0.2.16

fix: synchronize existing release PR title and summary (#88)

Existing release PR updates changed the signed branch contents but reused the PR without updating its title or body. Because Release PR Sync is now manual-only, the displayed version remained stale (herdr-linear-agent #102 prepared v0.8.0 but still advertised v0.7.2).

Synchronize title and body from validated artifact options when the normal apply path reuses the verified Server App-owned release PR, including idempotent recovery. Preserve ownership, branch/base checks and commit binding; do not change draft state. Extend the existing scratch native apply retry probe to deliberately stale the metadata and assert restoration without an extra commit. Prepare runtime 0.2.16.

Validation:
- 14 relevant securefix_gate tests and local all-target Clippy passed; independent focused security review passed.
- [Required CI](https://github.com/civitaspo/securefix-server/actions/runs/38644778440) passed standard tests, formatting, Clippy and workflow checks for candidate `84ed03b8491e73a494b9c215620df6b02415d657`.
- [Candidate scratch prepare](https://github.com/civitaspo/securefix-server/actions/runs/38644795923/job/116129850450) passed actual existing-PR title/body synchronization and same-commit idempotent retry, plus affected authorization checks. Client artifact smoke test also passed. Scratch fixtures were cleaned up. Unrelated merge/publication scenarios were not rerun.