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/components/NewGoalDialog.tsx

@@ -151,9 +151,9 @@ export function NewGoalDialog() {
         </div>
 
         {/* Title */}
-        <div className="px-4 pt-3">
+        <div className="px-4 pt-4 pb-2 shrink-0">
           <input
-            className="w-full text-base font-medium bg-transparent outline-none placeholder:text-muted-foreground/50"
+            className="w-full text-lg font-semibold bg-transparent outline-none placeholder:text-muted-foreground/50"
             placeholder="Goal title"
             value={title}
             onChange={(e) => setTitle(e.target.value)}