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/InlineEditor.tsx

@@ -1,7 +1,7 @@
 import { useState, useRef, useEffect, useCallback } from "react";
-import Markdown from "react-markdown";
 import { cn } from "../lib/utils";
 import { Button } from "@/components/ui/button";
+import { MarkdownBody } from "./MarkdownBody";
 import { MarkdownEditor } from "./MarkdownEditor";
 
 interface InlineEditorProps {
@@ -138,9 +138,7 @@ export function InlineEditor({
       onClick={() => setEditing(true)}
     >
       {value && multiline ? (
-        <div className="prose prose-sm prose-invert max-w-none prose-p:my-1 prose-ul:my-1 prose-ol:my-1 prose-li:my-0 prose-pre:my-2 prose-headings:my-2 prose-headings:text-sm">
-          <Markdown>{value}</Markdown>
-        </div>
+        <MarkdownBody>{value}</MarkdownBody>
       ) : (
         value || placeholder
       )}