Function extractLanguage

extractLanguage(input: DocumentInput): LanguageMetadata
Extract language and localization metadata from HTML.
Parameters
- input: DocumentInput
  Parsed HTML document or raw HTML string
Returns LanguageMetadata
Language metadata
Remarks
Extracts language information from HTML lang attribute, meta tags, and OpenGraph locale. Normalizes to provide a primary language and region.
Example
```
// With parsed document (recommended for multiple extractions)
const doc = parseHTML(htmlString);
const lang = extractLanguage(doc);

// Or directly with HTML string
const lang = extractLanguage(htmlString);
```
- Defined in src/metadata/language/extract.ts:39