Link the Space to its upstream model(s) and tag it

Adds `models:` and `tags:` to the README frontmatter, generated from the
spec in _shared/ rather than hand-written. `models:` is only set where the
weights are actually published on the Hub.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LJJXU9zyoDSBjApcUpteDt

README.md

@@ -6,6 +6,11 @@ colorTo: purple
 sdk: static
 pinned: false
 short_description: Reference for ByteDance Seedream 4.0 image model
+tags:
+  - text-to-image
+  - image-editing
+  - seedream
+  - wavespeed
 ---
 
 # Seedream 4.0