refactor: remove core-ui from main (scaffoldable via gen core-package ui)

Removal across all three consumers:
- apps/storybook: strips @repo/core-ui dep, clears stories glob (now []),
  removes globals.css import from preview.ts
- apps/web-next: strips @repo/core-ui dep + transpilePackages entry
- apps/web-tanstack: strips @repo/core-ui dep
- packages/core-ui: deleted entirely (28 files)

No app pages needed surgery — neither web-next nor web-tanstack source
files imported @repo/core-ui directly. The storybook app referenced it
only via the stories glob and the globals.css preview import.

Gates: 40/40 tasks successful, all 4 e2e byte-identical reconstructions
pass (realtime, events, trpc, ui).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/core-ui/src/atoms/label/index.ts

@@ -1 +0,0 @@
-export { Label, type LabelProps } from "./label";

packages/core-ui/src/atoms/label/label.test.tsx

@@ -1,16 +0,0 @@
-import { describe, it, expect } from "vitest";
-import { renderWithProviders } from "@repo/core-testing/react";
-import { screen } from "@testing-library/react";
-import { Label } from "./label";
-
-describe("Label", () => {
-  it("renders the label text", () => {
-    renderWithProviders(<Label htmlFor="email">Email</Label>);
-    expect(screen.getByText("Email")).toBeInTheDocument();
-  });
-
-  it("forwards htmlFor to associate with an input", () => {
-    renderWithProviders(<Label htmlFor="email">Email</Label>);
-    expect(screen.getByText("Email")).toHaveAttribute("for", "email");
-  });
-});

packages/core-ui/src/atoms/label/label.tsx

@@ -1,20 +0,0 @@
-import { forwardRef, type LabelHTMLAttributes } from "react";
-import { cn } from "../../lib/utils";
-
-export type LabelProps = LabelHTMLAttributes<HTMLLabelElement>;
-
-export const Label = forwardRef<HTMLLabelElement, LabelProps>(
-  ({ className, ...props }, ref) => {
-    return (
-      <label
-        className={cn(
-          "text-sm font-medium leading-none peer-disabled:cursor-not-allowed peer-disabled:opacity-70",
-          className
-        )}
-        ref={ref}
-        {...props}
-      />
-    );
-  }
-);
-Label.displayName = "Label";