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/styles/globals.css

@@ -1,26 +0,0 @@
-@import "tailwindcss";
-
-@theme {
-  --color-background: hsl(0 0% 100%);
-  --color-foreground: hsl(240 10% 3.9%);
-  --color-card: hsl(0 0% 100%);
-  --color-card-foreground: hsl(240 10% 3.9%);
-  --color-popover: hsl(0 0% 100%);
-  --color-popover-foreground: hsl(240 10% 3.9%);
-  --color-primary: hsl(240 5.9% 10%);
-  --color-primary-foreground: hsl(0 0% 98%);
-  --color-secondary: hsl(240 4.8% 95.9%);
-  --color-secondary-foreground: hsl(240 5.9% 10%);
-  --color-muted: hsl(240 4.8% 95.9%);
-  --color-muted-foreground: hsl(240 3.8% 46.1%);
-  --color-accent: hsl(240 4.8% 95.9%);
-  --color-accent-foreground: hsl(240 5.9% 10%);
-  --color-destructive: hsl(0 84.2% 60.2%);
-  --color-destructive-foreground: hsl(0 0% 98%);
-  --color-border: hsl(240 5.9% 90%);
-  --color-input: hsl(240 5.9% 90%);
-  --color-ring: hsl(240 5.9% 10%);
-  --radius-sm: 0.25rem;
-  --radius-md: 0.375rem;
-  --radius-lg: 0.5rem;
-}