fix: strip HTML tags from config.name when setting page title (#2690)

The `name` config option can contain HTML markup (e.g. `<img>` tags) for
rendering a logo in the sidebar. However, this raw HTML was being used
directly in `document.title`, causing browser tabs to show markup like
`<img src="logo.png">My Site - Page Title`.

Strip HTML tags from `name` before using it in the page title so that
only the plain text content appears in the browser tab.

Fixes #2610

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>