feat(ui): add auth pages, company rail, inbox redesign, and page improvements

Add Auth sign-in/sign-up page and InviteLanding page for invite acceptance.
Add CloudAccessGate that checks deployment mode and redirects to /auth when
session is required. Add CompanyRail with drag-and-drop company switching.
Add MarkdownBody prose renderer. Redesign Inbox with category filters and
inline join-request approval. Refactor AgentDetail to overview/configure/runs
views with claude-login support. Replace navigate() anti-patterns with <Link>
components in Dashboard and MetricCard. Add live-run indicators in sidebar
agents. Fix LiveUpdatesProvider cache key resolution for issue identifiers.
Add auth, health, and access API clients.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

ui/src/hooks/useKeyboardShortcuts.ts

@@ -4,9 +4,10 @@ interface ShortcutHandlers {
   onNewIssue?: () => void;
   onToggleSidebar?: () => void;
   onTogglePanel?: () => void;
+  onSwitchCompany?: (index: number) => void;
 }
 
-export function useKeyboardShortcuts({ onNewIssue, onToggleSidebar, onTogglePanel }: ShortcutHandlers) {
+export function useKeyboardShortcuts({ onNewIssue, onToggleSidebar, onTogglePanel, onSwitchCompany }: ShortcutHandlers) {
   useEffect(() => {
     function handleKeyDown(e: KeyboardEvent) {
       // Don't fire shortcuts when typing in inputs
@@ -15,6 +16,13 @@ export function useKeyboardShortcuts({ onNewIssue, onToggleSidebar, onTogglePane
         return;
       }
 
+      // Cmd+1..9 → Switch company
+      if ((e.metaKey || e.ctrlKey) && e.key >= "1" && e.key <= "9") {
+        e.preventDefault();
+        onSwitchCompany?.(parseInt(e.key, 10) - 1);
+        return;
+      }
+
       // C → New Issue
       if (e.key === "c" && !e.metaKey && !e.ctrlKey && !e.altKey) {
         e.preventDefault();
@@ -36,5 +44,5 @@ export function useKeyboardShortcuts({ onNewIssue, onToggleSidebar, onTogglePane
 
     document.addEventListener("keydown", handleKeyDown);
     return () => document.removeEventListener("keydown", handleKeyDown);
-  }, [onNewIssue, onToggleSidebar, onTogglePanel]);
+  }, [onNewIssue, onToggleSidebar, onTogglePanel, onSwitchCompany]);
 }