Backend: External V2 Request Tracking

External V2 handlers must preserve request-manager tracking contract.

Rationale:
- Request tracking is required for consistent response wrapping, observability, and request lifecycle management.

Scope:
- PR review policy for `domains/python/backend/app/src/api/routes_external/v2/**/views.py`.

Trigger:
- A PR changes endpoint handler logic in scope (excluding comment-only/format-only edits).

Approval checks:
1) Handler constructs typed `V2*ApiRequestValue` (or approved equivalent typed builder).
2) Handler executes request work inside `api_request_manager` context using request + api_request_value.
3) Handler returns via `MemManagedApiResponse(..., manager=manager)` for request-managed endpoints.
4) Changed endpoint tests are updated and include request-tracking contract assertions (or equivalent manager-integration coverage).

Evidence:
- Diff shows request value + manager context + managed response path.
- Tests validate manager/tracking behavior for changed endpoint.

Decision:
- Return NOT APPROVED when trigger is met and request-tracking contract checks are missing.