feat(system-tags): process vs chrome groups + WIP provisional auto-apply (#1464)

Backend for the system-tag behavior refactor (milestone #157). editor screenshot
moves from chrome (hidden) to the PROCESS group (shown, like wip); wip+editor gain
provisional auto-apply so they stop needing endless manual identification —
without a runaway loop.

- tag.py: split PRESENTATION_SYSTEM_TAGS → CHROME_SYSTEM_TAGS (banner) +
  PROCESS_SYSTEM_TAGS (wip, editor screenshot).
- heads.py: generalize presentation_auto_apply_sweep → system_tag_auto_apply_sweep
  (mode chrome|process). Same Guard 1 (skip human/confirmed) + Guard 2 (ring-loud
  conflict → PresentationReview). process mode uses source 'process_auto' and does
  NOT hide (hide is a gallery-query effect of group membership).
- training_data._AUTO_SOURCES += 'process_auto' → the head never trains on its own
  auto-applied output; only wip_title/manual train it (the runaway break).
- ml_settings: process_auto_apply_enabled (OFF, opt-in) + threshold + conflict
  threshold. presentation_review.mode ('chrome'|'process'). Migration 0086.
- gallery_service: default-hide reads CHROME only (editor now shows); Explore
  neighbors exclude the whole PROCESS group.
- tasks/ml + celery beat: scheduled_process_auto_apply (daily, opt-in); prune
  covers both modes.
- api: ml_admin process_* CRUD+validation; hidden-review returns mode.
- tests: rename chrome sweep calls; new test_process_auto_apply (apply, guards,
  mode flag, no-self-train); gallery test asserts editor now visible.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/test_gallery_service.py

@@ -82,24 +82,28 @@ async def _system_tag(db, name):
 
 @pytest.mark.asyncio
 async def test_scroll_hides_presentation_chrome_by_default(db):
-    # banner / editor screenshot (presentation system tags) are hidden from the
-    # default gallery; wip (also a system tag) is NOT — it's real, in-progress
-    # art (milestone 141). Seeded system tags survive the harness TRUNCATE.
-    imgs = await _seed_images(db, 3, sha_prefix="p")
+    # banner (chrome) is hidden from the default gallery; wip AND editor screenshot
+    # (the PROCESS system tags) are NOT — they're real art / process shots that stay
+    # visible (milestone 141 + #1464). Seeded system tags survive the harness TRUNCATE.
+    imgs = await _seed_images(db, 4, sha_prefix="p")
     banner = await _system_tag(db, "banner")
     wip = await _system_tag(db, "wip")
+    editor = await _system_tag(db, "editor screenshot")
     await db.execute(image_tag.insert().values(
         image_record_id=imgs[0].id, tag_id=banner.id, source="manual"))
     await db.execute(image_tag.insert().values(
         image_record_id=imgs[1].id, tag_id=wip.id, source="manual"))
+    await db.execute(image_tag.insert().values(
+        image_record_id=imgs[3].id, tag_id=editor.id, source="manual"))
     await db.flush()
     svc = GalleryService(db)
 
-    # Default: the banner image is hidden; the wip image + the plain image stay.
+    # Default: only the banner image is hidden; wip + editor + plain all stay.
     default_ids = {i.id for i in (await svc.scroll(cursor=None, limit=10)).images}
     assert imgs[0].id not in default_ids      # banner hidden
     assert imgs[1].id in default_ids          # wip visible
     assert imgs[2].id in default_ids          # plain visible
+    assert imgs[3].id in default_ids          # editor screenshot visible (#1464)
 
     # include_hidden surfaces the banner image (the Hidden view).
     shown = {i.id for i in (