Manage the built-in daemon from one place in settings (#1938)

* feat(settings): consolidate daemon management into the host page

The app-level Daemon section and the localhost host page rendered the
same daemon card in two places. The host page is now the single home:
the Host sidebar group leads with Overview, and a desktop-only "Enable
built-in daemon" option in the host switcher recovers a removed
localhost connection. Old settings/daemon deep links redirect
(COMPAT-tagged).

* fix(settings): hide daemon recovery option when the server id probe fails

Review feedback: !query.isLoading treated an errored IPC probe as
resolved, so the recovery affordance could show without knowing the
local server id. Replace the resolved-boolean hook with a single
discriminated state hook (loading | error | resolved) — errors hide the
affordance and fall back to the settings root in the redirect. Also
collapses the two query subscriptions per caller into one.

* fix(settings): keep daemon recovery reachable when no hosts remain

Review feedback: removing localhost as the only host takes the settings
sidebar down its no-host branch, which never mounts the host picker —
so the "Enable built-in daemon" option was unreachable in the most
common recovery case. The sidebar now owns the single hook call, passes
it to the picker, and renders the same action as a sidebar row next to
"Add host" when no hosts exist.

* test(e2e): update settings host header to Overview

Test drift: the host section's sidebar/header label was intentionally
renamed to "Overview"; the spec still asserted the old "Host" title.
Also assert the retired app-level Daemon row stays absent.

packages/app/e2e/helpers/settings.ts

@@ -371,6 +371,7 @@ export async function expectRetiredSidebarSectionsAbsent(page: Page): Promise<vo
   await expect(sidebar.getByRole("button", { name: "General", exact: true })).toBeVisible();
   await expect(sidebar.getByRole("button", { name: "Diagnostics", exact: true })).toBeVisible();
   await expect(sidebar.getByRole("button", { name: "About", exact: true })).toBeVisible();
+  await expect(sidebar.getByRole("button", { name: "Daemon", exact: true })).toHaveCount(0);
 
   // Host group rows are now flat top-level sections (no drill-in).
   await expect(sidebar.getByTestId("settings-host-section-connections")).toBeVisible();

packages/app/e2e/settings-host-page.spec.ts

@@ -64,7 +64,7 @@ test.describe("Settings host page", () => {
     await openSettingsHost(page, serverId);
 
     await openHostSection(page, serverId, "host");
-    await expectSettingsHeader(page, "Host");
+    await expectSettingsHeader(page, "Overview");
     await expectHostLabelDisplayed(page);
     await expectHostActionCards(page, serverId);
   });