fix(inbox): restore Scout in the source filter dropdown (#2587)

Author: andrewm4894

packages/ui/src/features/inbox/CLAUDE.md

@@ -106,7 +106,7 @@ When adding or changing UI, reuse those primitives first. Avoid encoding one-off
 - Do not reuse the deleted legacy `ReportListRow`, `ReportDetailPane`, or old list/detail stores.
 - Do not put page-level Inbox title or navigation into the global app header; `InboxView` owns the Inbox page chrome.
 - Do not add a configure shortcut back into the Inbox header; Responders configuration is a sidebar destination.
-- Do not add Scout UI until a corresponding backend exists in this repo.
+- Scout (`signals_scout`) is a real Cloud source product. Keep it covered wherever source products surface: `INBOX_SOURCE_OPTIONS`, `SOURCE_PRODUCT_META`, and the scout-name display in `SignalCard`. Do not add Scout management UI (fleet configuration, run history) until a corresponding backend exists in this repo.
 - Do not put preview shims or mock report data in `apps/code/index.html`; the app shell should stay minimal.
 - Do not call `electronTRPC` directly from Inbox code. Use the existing API client, React Query hooks, or tRPC client wrappers.
 - Do not preserve compatibility with unshipped intermediate UI shapes on this branch. Replace them cleanly.

packages/ui/src/features/inbox/filterOptions.tsx

@@ -3,6 +3,7 @@ import {
   BugIcon,
   CalendarPlus,
   Clock,
+  CompassIcon,
   GithubLogoIcon,
   KanbanIcon,
   LifebuoyIcon,
@@ -99,6 +100,7 @@ export const INBOX_SOURCE_OPTIONS: {
     icon: <LifebuoyIcon size={14} />,
   },
   { value: "pganalyze", label: "pganalyze", icon: <PgAnalyzeIcon size={14} /> },
+  { value: "signals_scout", label: "Scout", icon: <CompassIcon size={14} /> },
 ];
 
 export function inboxSortOptionKey(