refactor(platforms): retire deviantart end-to-end (#3069)

Executes the 2026-07-05 product decision (FC downloaders = art-dedicated
services only), which removed Twitter/X and Bluesky but left deviantart
fully wired for seven weeks — the half-retired state rule 22 exists to
prevent.

Removed: the PlatformInfo module and its registry entry, the gallery-dl
extractor block, extension_service's artist-page pattern, the extension's
PLATFORMS + PLATFORM_ARTIST_PATTERNS entries, its manifest host permission
and content-script match, the frontend icon/colour/label, and the operator-
facing "supported platforms" list that still advertised it.

Two judgment calls, both recorded in migration 0088:

  * existing `source` rows are DISABLED, not deleted. The row is the only
    record of the artist's DeviantArt URL. Disabling is also required for
    correctness rather than tidiness: with the platform unregistered the
    download path falls through to gallery-dl, which carries its OWN
    deviantart extractor, so an enabled row would have kept downloading
    from a dropped platform.
  * the `credential` row IS deleted — a live session cookie for a site FC
    will never call again.

Adds the invariant whose absence is why manifest.json drifted in the first
place: nothing tied its domain lists back to the platform table. The
extension suite now asserts both directions, plus that no host permission
belongs to an unclaimed domain (`*://*/*` exempted — FC is self-hosted at
an operator-chosen URL the extension cannot enumerate).

Extension version 1.0.10 -> 1.0.11: ci.yml's guard hard-fails a packaged
extension change without a bump. No release is cut — build.yml's
sign-extension job only runs on main.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

backend/app/services/platforms/__init__.py

@@ -8,9 +8,10 @@ PLATFORMS below. Sidecar parsing, cookie materialization, and
 
 Lifted from GallerySubscriber's
 ~/Nextcloud/Projects/GallerySubscriber/backend/app/api/platforms.py
-and ~/.../extension/lib/platforms.js. Six platforms; auth_type and
+and ~/.../extension/lib/platforms.js. Five platforms; auth_type and
 URL patterns match GS exactly so the existing browser extension
-hits FC unmodified.
+hits FC unmodified. deviantart was dropped at #3069 (2026-08-27) —
+FC downloaders are art-dedicated services only.
 """
 
 from .base import (
@@ -18,7 +19,6 @@ from .base import (
     DEFAULT_EXTERNAL_POST_ID_KEYS,
     PlatformInfo,
 )
-from .deviantart import INFO as _DEVIANTART
 from .discord import INFO as _DISCORD
 from .hentaifoundry import INFO as _HENTAIFOUNDRY
 from .patreon import INFO as _PATREON
@@ -33,7 +33,6 @@ PLATFORMS: dict[str, PlatformInfo] = {
         _HENTAIFOUNDRY,
         _DISCORD,
         _PIXIV,
-        _DEVIANTART,
     )
 }
 

backend/app/services/platforms/base.py

@@ -63,7 +63,7 @@ class PlatformInfo:
     # Synthesize a post permalink from sidecar data. Required when
     # gallery-dl's `url` field is the file/CDN URL rather than the post
     # permalink (subscribestar/pixiv/hf/discord). None = trust the bare
-    # `url` field (patreon, deviantart).
+    # `url` field (patreon).
     derive_post_url: Callable[[dict], str | None] | None = None
 
     # Post-process the materialized cookies.txt for gallery-dl. Used by

backend/app/services/platforms/deviantart.py

@@ -1,23 +0,0 @@
-"""DeviantArt — no exercised quirks yet.
-
-No operator-owned DeviantArt archive existed at the 2026-05-27 sidecar
-audit, so we don't know yet whether DA's gallery-dl sidecars are
-well-behaved or have their own quirks. When DA gets exercised for the
-first time, add `derive_post_url` / `augment_cookies` here as needed.
-"""
-
-from .base import GD_DEFAULTS, PlatformInfo
-
-INFO = PlatformInfo(
-    key="deviantart",
-    name="DeviantArt",
-    description="Download artwork from DeviantArt artists",
-    auth_type="cookies",
-    requires_auth=False,
-    url_pattern=r"^https?://(www\.)?deviantart\.com/",
-    url_examples=[
-        "https://www.deviantart.com/example-artist",
-        "https://www.deviantart.com/example-artist/gallery",
-    ],
-    default_config={**GD_DEFAULTS, "content_types": ["gallery"]},
-)