app.didpic.write.uploadBlob

Upload raw image bytes to the authenticated viewer's own PDS, mediated by the AppView using its server-held session (confidential OAuth client only). Mirrors com.atproto.repo.uploadBlob. The returned blob ref is passed into createPost, createComment, or putProfile to attach it to a record. This endpoint applies no per-context size limit beyond a generous ceiling — the PDS enforces the real limit (post/comment 5MB, avatar 1MB, banner 2MB) when the blob is actually attached to a record.