Reference existing JSDoc examples instead of maintaining a separate one in
`docs/patterns.ts`:
- Vanilla JS: `applyDocumentTheme_fromHostContext` from `styles.examples.ts`
- React: `useDocumentTheme_conditionalRender` for reactive theme reading
Expand `applyDocumentTheme_fromHostContext` example to show both the
`onhostcontextchanged` handler and initial theme application after `connect()`.
Note in the docs that `useHostStyles()` applies theme automatically, so React
apps don't need additional setup unless they want to read the theme reactively
for conditional rendering.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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