prove per-component lifecycle namespaces stay isolated

[joshua-temple]

Problem / why

The hotfix / rollback / release changes each segment a namespace; an end-to-end proof should
confirm a full per-component lifecycle (hotfix, then rollback, then release reaping) stays
confined to one component while a sibling is unaffected.

Scope (firm intent)

• An e2e exercising a component's hotfix, rollback, and rc-tag reaping in sequence and
  asserting the sibling component's branches, refs, tags, and state are untouched throughout.

Files / areas touched

• e2e/ per-component lifecycle scenario.

Tests and coverage required

• The combined lifecycle isolation e2e described above.

Acceptance criteria

• A full per-component lifecycle leaves every sibling component fully isolated.

Dependencies

Blocked by R1, R2, R3.

[joshua-temple]

Implemented and merged via #528.