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)

actions/update-stock.ts

@@ -0,0 +1,47 @@
+import { defineAction } from "@agent-native/core/action";
+import { and, eq } from "@agent-native/core/db/schema";
+import { z } from "zod";
+
+import { getDb } from "../server/db/index.js";
+import { stocks } from "../server/db/schema.js";
+
+export default defineAction({
+  description:
+    "Update fields on an existing stock listing (patch — only pass the fields that change). Use this to edit price, change percent, sector, or toggle the watchlist.",
+  schema: z.object({
+    id: z.string().describe("Stock listing id"),
+    companyName: z.string().optional(),
+    exchange: z.string().optional(),
+    sector: z.string().optional(),
+    currency: z.string().optional(),
+    price: z.coerce.number().optional(),
+    changePercent: z.coerce.number().optional(),
+    marketCap: z.coerce.number().optional(),
+    watchlisted: z
+      .enum(["true", "false"])
+      .optional()
+      .describe("Set to \"true\" or \"false\" to toggle the watchlist"),
+  }),
+  http: { method: "PUT" },
+  run: async (args, ctx) => {
+    if (!ctx?.userEmail) throw new Error("Authentication required.");
+    const { id, watchlisted, ...rest } = args;
+    const db = getDb();
+
+    const patch: Record<string, unknown> = { ...rest };
+    if (watchlisted !== undefined) patch.watchlisted = watchlisted === "true";
+    if (Object.keys(patch).length === 0) {
+      throw new Error("No fields to update.");
+    }
+    patch.updatedAt = new Date().toISOString();
+
+    const updated = await db
+      .update(stocks)
+      .set(patch)
+      .where(and(eq(stocks.id, id), eq(stocks.ownerEmail, ctx.userEmail)))
+      .returning();
+
+    if (!updated[0]) throw new Error("Stock not found.");
+    return updated[0];
+  },
+});