refactor(snippets): adopt alias/title model and markdown UX

- rename snippet identity from name to alias and add required title fields

- migrate snippet API, forms, cards, and detail views to alias/title semantics

- render markdown descriptions with short card previews and split vendor chunks

client/src/ui/index.ts

@@ -45,6 +45,9 @@ export type { CodeBlockProps } from './CodeBlock/CodeBlock';
 export { CodeEditor } from './CodeEditor/CodeEditor';
 export type { CodeEditorProps } from './CodeEditor/CodeEditor';
 
+export { MarkdownContent } from './MarkdownContent/MarkdownContent';
+export type { MarkdownContentProps } from './MarkdownContent/MarkdownContent';
+
 export { ContextMenu } from './ContextMenu/ContextMenu';
 export type { ContextMenuProps, ContextMenuItem } from './ContextMenu/ContextMenu';