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)

server/plugins/agent-chat.ts

@@ -6,16 +6,25 @@ import {
 
 import actionsRegistry from "../../.generated/actions-registry.js";
 
-const INITIAL_TOOL_NAMES = ["view-screen", "navigate", "hello"];
+const INITIAL_TOOL_NAMES = [
+  "view-screen",
+  "navigate",
+  "hello",
+  "list-stocks",
+  "get-stock",
+  "add-stock",
+  "update-stock",
+  "delete-stock",
+];
 
 export default createAgentChatPlugin({
   appId: "app",
   actions: loadActionsFromStaticRegistry(actionsRegistry),
   initialToolNames: INITIAL_TOOL_NAMES,
   resolveOrgId: async (event) => (await getOrgContext(event)).orgId,
-  systemPrompt: `You are the Chat app agent.
+  systemPrompt: `You are the Chat app agent for a minimal stock listing app.
 
-This is a minimal chat-first Agent-Native app. The chat is the product surface, and actions are the contract shared by chat, UI, HTTP, MCP, A2A, and CLI.
+The chat is the product surface, and actions are the contract shared by chat, UI, HTTP, MCP, A2A, and CLI. The app tracks a per-user list of stock tickers (symbol, company name, exchange, sector, price, change percent, market cap, watchlisted) at the /stocks page, backed by the list-stocks, get-stock, add-stock, update-stock, and delete-stock actions.
 
 Use actions as the source of truth. Start by inspecting the current screen when context matters. When the user asks to extend this app, keep the change small and agent-native: add or update actions, expose useful UI, and keep application state/navigation visible to the agent.`,
 });