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/ui/badge.tsx

@@ -0,0 +1,36 @@
+import * as React from "react"
+import { cva, type VariantProps } from "class-variance-authority"
+
+import { cn } from "@/lib/utils"
+
+const badgeVariants = cva(
+  "inline-flex items-center rounded-full border px-2.5 py-0.5 text-xs font-semibold transition-colors focus:outline-none focus:ring-2 focus:ring-ring focus:ring-offset-2",
+  {
+    variants: {
+      variant: {
+        default:
+          "border-transparent bg-primary text-primary-foreground hover:bg-primary/80",
+        secondary:
+          "border-transparent bg-secondary text-secondary-foreground hover:bg-secondary/80",
+        destructive:
+          "border-transparent bg-destructive text-destructive-foreground hover:bg-destructive/80",
+        outline: "text-foreground",
+      },
+    },
+    defaultVariants: {
+      variant: "default",
+    },
+  }
+)
+
+export interface BadgeProps
+  extends React.HTMLAttributes<HTMLDivElement>,
+    VariantProps<typeof badgeVariants> {}
+
+function Badge({ className, variant, ...props }: BadgeProps) {
+  return (
+    <div className={cn(badgeVariants({ variant }), className)} {...props} />
+  )
+}
+
+export { Badge, badgeVariants }