Phase 5: Remove the MauiProgram.Container bridge

Scope:\n- Delete MauiProgram.Container once no code depends on it.\n- Remove any remaining fallback access patterns.\n- Leave the app using normal DI/composition root boundaries only.\n\nAcceptance criteria:\n- MauiProgram has no global service locator bridge.\n- Repository search finds no MauiProgram.Container references.\n- Build still succeeds after the cleanup.