feat(ui-models): tag the provider rows this deployment declared

A row's stored profile could not tell a hand-declared gateway from a
shipped provider whose models someone narrowed — both look identical from
outside the adapter — so the Models page had no way to mark the routes a
deployment added itself.

The directory entry now carries `declared`, answered by the owning adapter
against its own installed catalog, and the page renders a Custom tag from
it. Absence stays "this adapter draws no such distinction" rather than
"shipped", so a route no adapter claims is labelled neither way.

Also records the default-route work's Agent Note and the e2e evidence for
all three changes: the composer switch writing the section, and the Models
page declaring a route with its own reasoning effort.

apps/web/tsconfig.json

@@ -37,6 +37,7 @@
     "tests/details-session-lifecycle.e2e.ts",
     "tests/settings-chrome.e2e.ts",
     "tests/models-settings.e2e.ts",
+    "tests/default-model.e2e.ts",
     "tests/onboarding-deepseek-config.e2e.ts",
     "tests/remote-welcome.e2e.ts",
     "tests/workspace-management.e2e.ts",