fix(ai): correct stale role-hierarchy and file-listing claims

Codex review of the dual-agent handoff migration flagged factual errors
carried over verbatim from the pre-migration CLAUDE.md. All claims
verified against the live code before correction.

PROJECT_CONTEXT.md — SaaS shape:
- Role hierarchy was `super_admin > team_admin > engineer > viewer`,
  but `backend/app/core/permissions.py:4` and
  `frontend/src/hooks/usePermissions.ts:4` both define it as
  `super_admin > owner > engineer > viewer`. The `team_admin` concept
  exists separately as an orthogonal team-scoped gate
  (`require_team_admin`, `is_team_admin=True` + valid `team_id`), not
  a level in the primary hierarchy.
- Dep list was missing `require_account_owner` and `require_team_admin`,
  both present in `backend/app/api/deps.py`.

PROJECT_CONTEXT.md — directory tree:
- `api/endpoints/` comment listed 11 routers; `api/router.py` actually
  registers 50+. Replaced with a summary that points at `router.py` as
  the source of truth instead of trying to maintain a freezing list.
- `services/psa/` comment omitted `exceptions.py` and `ticket_context.py`,
  both present in the directory.

CURRENT_TASK.md + TODO.md:
- Replaced `<!-- EXAMPLE -->` placeholders with clearer empty-state
  sentinels so a resume agent sees "no real task yet" at a glance
  rather than placeholder acceptance criteria that look unresolved.

SESSION_LOG.md updated with a follow-up bullet documenting this pass.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

.ai/TODO.md

@@ -5,8 +5,8 @@
 
 ## Up next
 
-- [ ] (seed entry — replace with real next-up items)
+- [ ] No queued backlog yet.
 
 ## Backlog
 
-- [ ] (seed entry — replace with real backlog items)
+- [ ] No queued backlog yet.