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/api/agents.ts

@@ -22,6 +22,15 @@ export interface AdapterModel {
   label: string;
 }
 
+export interface ClaudeLoginResult {
+  exitCode: number | null;
+  signal: string | null;
+  timedOut: boolean;
+  loginUrl: string | null;
+  stdout: string;
+  stderr: string;
+}
+
 export interface OrgNode {
   id: string;
   name: string;
@@ -87,4 +96,5 @@ export const agentsApi = {
       idempotencyKey?: string | null;
     },
   ) => api.post<HeartbeatRun | { status: "skipped" }>(`/agents/${id}/wakeup`, data),
+  loginWithClaude: (id: string) => api.post<ClaudeLoginResult>(`/agents/${id}/claude-login`, {}),
 };