Plugin API exposes product image analysis status

GET /plugin/products/{id_or_ref} now surfaces the Gemini analysis lifecycle on every embedded product image so plugins can wait for a photo to be analyzed before submitting jobs against it.

GET /api/v1/plugin/products/{id_or_ref} now returns two additional fields on each embedded images[] entry: analysis_status ('pending' | 'processing' | 'described' | 'error') and analyzed_at (ISO timestamp or null). The fields reflect the lifecycle of the background Gemini vision analysis that populates product metadata from the uploaded image.

Plugin clients SHOULD wait for analysis_status='described' before submitting POST /jobs against the image's asset_id; otherwise the worker may stall with PREPARE_PHOTOS_TIMEOUT. This is purely additive — existing fields are unchanged, no scope changes, and analysis_status of legacy rows is populated from the same column that has driven the worker behavior since the catalog launched.