E2E: sequence ordering — 3 jobs at same phase run in ascending order

**Epic:** #1082

Package 3 job descriptors at the same phase with `sequence: 30, 10, 20`. Each job writes its sequence number and timestamp to a shared volume or log. Assert execution order is 10 → 20 → 30.

## Acceptance Criteria
- [ ] Jobs run in ascending sequence order (10 → 20 → 30)
- [ ] Test covers both upgrade (frozen) and install (pre-install) contexts
- [ ] Deterministic on 5 consecutive runs

Start by reviewing epic #1082 and locating the repository's E2E harness for job descriptors. Add coverage for three same-phase jobs in upgrade and install contexts, then run the test five consecutive times to confirm deterministic 10 → 20 → 30 ordering.

Written by the indexing model from the issue text.