Add Visage v2.8.0 - facial recognition plugin

[cc1234475]

Visage v2.8.0

Facial recognition plugin update for Stash.

New

• Performer page: Identify from image button (next to Merge). Searches the performer's image against StashDB and links matching stash IDs without touching the scene ops menu.
• Confirm flow in the face match modal appends and dedupes stash_ids, existing links preserved.

Changed

• 4 new UI strings translated across all 34 locales.
• Routing/mount supports /performers/:id in addition to scenes and images.

CSP

connect-src unchanged: HF production endpoint + http://localhost:7860 only.

Forum thread: https://discourse.stashapp.cc/t/visage/11785