Bulk-apply image alt text

The audit's vision pass looks at each image and writes an accurate, descriptive alt text (4-12 words, no “image of”). Bulk apply pushes them all to your Media Library.

• Duplicate images (the same file used on many pages) are de-duplicated, so each Media Library item is written once.
• Existing non-empty alts are kept.
• Alt text is set on the Media Library attachment, the canonical, SEO-correct place.