Make the admin control domain own its handlers and explicit state

[tiammomo]

Summary

The admin control router owns paths for aliases, settings, configuration reload, Provider probes, and router status, but its handlers and state dependencies remain in the 8,000-line root routes module. Complete this domain slice so registration, handlers, and dependencies have one owner.

Actual behavior

src/routes/admin_control.rs delegates all six control endpoints to functions in src/routes.rs. The handlers extract the process-wide AppState and rely on its temporary Deref bridge, leaving the control domain's dependencies implicit and keeping configuration behavior coupled to the root HTTP shell.

Expected behavior

src/routes/admin_control.rs owns the endpoint handlers and private validation types, and extracts a dedicated Axum FromRef substate containing only the application services used by control operations. The root routes module retains shared cross-domain policy helpers and application composition only.

Steps to reproduce

Inspect src/routes/admin_control.rs and run rg -n 'admin_(aliases|create_alias|delete_alias|settings|reload_config|update_settings|test_provider|router_status)' src/routes.rs src/routes/admin_control.rs. Registrations and implementations have different owners, and the handlers extract State.

Environment

ModelPort main plus the reviewed route-composition and application-state boundary changes from Issues #44 and #46; Rust/Axum 0.8.

Acceptance criteria

• The admin control module owns all handlers for its existing route inventory; those handlers extract an explicit control-domain substate through Axum FromRef instead of AppState; reusable cross-domain helpers remain centralized without circular module dependencies; architectural regression coverage prevents the handlers from returning to the root routes module; all focused and repository-wide checks pass; no endpoint, response schema, configuration key, persistence format, Provider behavior, dependency, or deployment change is introduced.