Add minimal stock listing app: actions, Postgres schema, stocks page, Claude Agent SDK harness

- Add stocks table (server/db) with list/get/add/update/delete actions, scoped
  per user, backing both the chat agent and the /stocks UI via
  useActionQuery/useActionMutation
- Add mobile-first /stocks page (shadcn table/cards, watchlist, search) and
  wire it into the sidebar, navigation state, and view-screen context
- Install the platform's Claude Agent SDK harness (server/plugins,
  server/routes/api/claude-agent) so the app agent runs on the platform's own
  Claude subscription instead of the Builder.io gateway; fix the vendored
  turn.post.ts route to resolve the session and wrap it in
  runWithRequestContext, since custom /api/ routes aren't auto-wrapped in
  request context the way /_agent-native/actions/* are
- Add shadcn table/badge/dialog/select components (Tabler icons, not lucide)

app/components/layout/Sidebar.tsx

@@ -14,6 +14,7 @@ import {
   type ChatHistoryItem,
 } from "@agent-native/toolkit/chat-history";
 import {
+  IconChartLine,
   IconLayoutSidebarLeftCollapse,
   IconLayoutSidebarLeftExpand,
   IconMessageCircle,
@@ -39,6 +40,12 @@ const navItems = [
     href: "/",
     view: "chat",
   },
+  {
+    icon: IconChartLine,
+    labelKey: "navigation.stocks",
+    href: "/stocks",
+    view: "stocks",
+  },
 ];
 
 const bottomNavItems = [