0c4b8aef8c
Final piece of the artist decoupling. (1) Identity-by-source: quick_add_source resolves the artist by an existing (platform, url) Source first, so a re-add reuses the artist even after it was renamed (its frozen slug no longer matches the name) — a slug-based lookup would have duplicated it. (2) Pixiv naming: a new pixiv source resolves the real display name via the app API (PixivClient .resolve_display_name → /v1/user/detail) using the stored token, so the artist is 'Kurotsuchi Machi' not '12345678' — and its name-derived slug matches what a native download produces, unifying them. Falls back to the numeric id when no token/crypto. ExtensionService gains the crypto seam; the endpoint passes it. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01CDgx8bQS5YrGRK76v8HUnM