Remove Storybook + unused components

[cte]

Description

We're not getting any value at the moment from Storybook or these half-baked components, so let's clean them up.

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Important

Remove Storybook and unused components, update configurations accordingly.

• Removal of Storybook:
  • Deleted Storybook configuration files: main.ts, preview.ts, vscode.css in .storybook.
  • Removed Storybook scripts from package.json.
  • Removed Storybook dependencies from package.json.
• Removal of Unused Components:
  • Deleted Chat components in webview-ui/src/components/ui/chat.
  • Deleted Markdown components in webview-ui/src/components/ui/markdown.
  • Removed related story files in webview-ui/src/stories.
• Configuration Updates:
  • Updated knip.json to remove Storybook entries and adjust project paths.

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