Adds `Permission.USER_MANAGE = "user.manage"` to the F11 matrix. rt_lead
already holds ALL_PERMISSIONS so GROUP_PERMISSIONS is unchanged — rt_lead
gets the new permission automatically, rt_operator and soc_analyst get 403.
Alembic migration `202605230001_add_user_manage_permission`:
- inserts the `user.manage` row into `permission`,
- inserts the `(rt_lead, user.manage)` link into `group_permission`,
- exposes `_DELTA_PERMISSIONS` / `_DELTA_GROUP_PERMISSIONS` for parity tests.
The previous `test_frozen_*_matches_runtime` invariant (MA3) is generalised
to "runtime = initial frozen ∪ deltas of every migration in `_DELTAS`". New
migrations register themselves there without editing the historical one.
Verbatim wording from spec-analyst is recorded as D-015 in
`tasks/spec-decisions.md` (separate commit).
Code-review MAJOR MA3. The initial Alembic migration imported the live
`mimic.rbac.matrix.GROUP_PERMISSIONS` to seed the `permission` / `group` /
`group_permission` rows. That breaks the Alembic invariant "a migration
produces the same schema regardless of when you replay it": a future tweak
to the runtime matrix would silently change the seeded baseline on a fresh
DB.
Two changes:
1. The migration now carries an *inline frozen snapshot* of the F11 matrix
(`_PERMISSIONS_FROZEN`, `_GROUP_PERMISSIONS_FROZEN`, `_GROUP_DESCRIPTIONS`).
The seed reads from these tuples/dicts only. If the canonical matrix
evolves, the next migration is responsible for the delta.
2. A new unit test `test_migration_seed_matches_current_matrix` enforces
that the frozen seed equals the runtime `Permission` enum and
`GROUP_PERMISSIONS` mapping. Drift now fails CI loudly with a hint to
write a new migration instead of editing the existing one.
Also: docstring no longer mentions `ttp_version` (M8 follow-up).
