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/EntityRow.tsx

@@ -1,4 +1,5 @@
 import { type ReactNode } from "react";
+import { Link } from "react-router-dom";
 import { cn } from "../lib/utils";
 
 interface EntityRowProps {
@@ -8,6 +9,7 @@ interface EntityRowProps {
   subtitle?: string;
   trailing?: ReactNode;
   selected?: boolean;
+  to?: string;
   onClick?: () => void;
   className?: string;
 }
@@ -19,19 +21,20 @@ export function EntityRow({
   subtitle,
   trailing,
   selected,
+  to,
   onClick,
   className,
 }: EntityRowProps) {
-  return (
-    <div
-      className={cn(
-        "flex items-center gap-3 px-4 py-2 text-sm border-b border-border last:border-b-0 transition-colors",
-        onClick && "cursor-pointer hover:bg-accent/50",
-        selected && "bg-accent/30",
-        className
-      )}
-      onClick={onClick}
-    >
+  const isClickable = !!(to || onClick);
+  const classes = cn(
+    "flex items-center gap-3 px-4 py-2 text-sm border-b border-border last:border-b-0 transition-colors",
+    isClickable && "cursor-pointer hover:bg-accent/50",
+    selected && "bg-accent/30",
+    className
+  );
+
+  const content = (
+    <>
       {leading && <div className="flex items-center gap-2 shrink-0">{leading}</div>}
       <div className="flex-1 min-w-0">
         <div className="flex items-center gap-2">
@@ -47,6 +50,20 @@ export function EntityRow({
         )}
       </div>
       {trailing && <div className="flex items-center gap-2 shrink-0">{trailing}</div>}
+    </>
+  );
+
+  if (to) {
+    return (
+      <Link to={to} className={cn(classes, "no-underline text-inherit")} onClick={onClick}>
+        {content}
+      </Link>
+    );
+  }
+
+  return (
+    <div className={classes} onClick={onClick}>
+      {content}
     </div>
   );
 }