* Flatten settings sidebar with a host picker
Settings had two implicit tiers: app-level sections as flat sidebar rows,
and per-host settings hidden behind a drill-in to one monolithic host page.
This flattens both into a single sidebar with an "App" group and a "Host"
group, where the host's settings are top-level rows scoped by a host picker.
- Split the monolithic HostPage into four section pages: Connections,
Orchestration (was the unnamed inject-tools + system-prompt block),
Providers, and Daemon (status, updates, restart, remove).
- Host picker reuses the canonical <Combobox> sidebar host switcher; defaults
to the local host so a single-local-host user never thinks about "the daemon".
- Host sections become real sub-routes (/settings/hosts/[id]/[section]); the
old /settings/hosts/[id] redirects to the connections section, so existing
deep links (pairing, workspace, open-project) keep working.
- "Open providers" from the project screen now lands on the Providers section.
* Fix e2e host-settings navigation for the flat sidebar
The flat-settings refactor moved host settings onto separate section pages,
but three e2e helpers still expected the old monolithic host page:
- openDesktopSettings: the daemon-lifecycle card now lives on the Daemon
section — navigate there before asserting it.
- acp catalog: "Add provider" now lives on the Providers section — open that
section before opening the add-provider modal.
- openAddHostFlow: "Add host" is now an item inside the host picker (Combobox),
not a standalone button — open the picker first.
Test-only; no product changes. Fixes the 8 playwright failures on this branch.
