chore: exclude stories from tsc type checking

Storybook CSF4 type inference generates massive .d.ts files for stories
(e.g. Card.stories.d.ts grew to 1.4MB by inlining all React HTML/ARIA
prop types). Excluding stories from tsc saves ~18s emit time, ~142MB
memory, and prevents unnecessary .d.ts bloat in dist-types.

No production code imports stories files, so this is safe.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Signed-off-by: Fredrik Adelöw <freben@spotify.com>

tsconfig.json

@@ -8,6 +8,7 @@
     "plugins/*/dev",
     "plugins/*/migrations"
   ],
+  "exclude": ["**/*.stories.ts", "**/*.stories.tsx"],
   "compilerOptions": {
     "outDir": "dist-types",
     "rootDir": ".",