feat(ccip): automation + reference quality — keep identity flowing hands-free (#114)

Works through the optional CCIP ideas + the "keep moving even if I forget" ask:

AUTOMATION (no button needed):
- Hourly beat auto-enqueues CCIP backfill — new images get embedded (and errored
  ones retried) on their own; the queue never goes idle waiting for a click.
- CCIP auto-apply: a daily sweep tags confident matches (source='ccip_auto') so
  identity tags keep flowing. ON by default (opt-out, like head auto-apply);
  ml_settings.ccip_auto_apply_enabled + _threshold (0.92, above the suggest cut),
  migration 0064. Vectorized (one matmul + reduceat per image), reversible, skips
  already-applied/rejected. Switch + threshold in the GPU agent card; GET/PATCH
  /api/ml/settings; auto_applied count in /api/ccip/overview.

REFERENCE QUALITY (the over-fire root cause):
- character_references now draws ONLY from single-character images — on a
  multi-character image the tag is image-level, so every figure would otherwise
  pollute each character's prototypes (a 2-char image tagged 'Velma' made
  Daphne's figure a Velma reference). This is the contamination behind residual
  over-firing.
- Cached on a cheap signature (char-tag count + ccip-region count/max-id) so the
  reference load isn't redone on every modal open.

Tests: multi-character image not used as a reference; auto-apply tags a confident
match as ccip_auto.

NEXT (not done, confirmed): comic-panel cropping + SigLIP concept crops ("spot
interesting content").

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Ttrj5P7upUTueSfoJcxEqa

tests/test_ccip.py

@@ -1,6 +1,7 @@
 """CCIP few-shot character matcher (#114). numpy cosine on stored vectors — no
 model needed, so it runs in CI with synthetic CCIP vectors."""
 import pytest
+from sqlalchemy import select
 
 from backend.app.models import ImageRecord, ImageRegion, TagKind
 from backend.app.models.tag import image_tag
@@ -103,3 +104,40 @@ async def test_threshold_gates_borderline_match(db):
 
     assert any(m["tag_id"] == raven.id for m in await match_image(db, query.id, 0.85))
     assert await match_image(db, query.id, 0.95) == []
+
+
+@pytest.mark.asyncio
+async def test_multi_character_image_not_used_as_reference(db):
+    # A figure on a 2-character image is ambiguous (tag is image-level), so it
+    # must NOT seed either character's prototypes — else it'd match both.
+    raven = await TagService(db).find_or_create("Raven", TagKind.character)
+    daphne = await TagService(db).find_or_create("Daphne", TagKind.character)
+    multi = await _img(db, "j" * 64)
+    await _figure(db, multi.id, _ccip(0))
+    await _tag_image(db, multi.id, raven.id)
+    await _tag_image(db, multi.id, daphne.id)
+    query = await _img(db, "k" * 64)
+    await _figure(db, query.id, _ccip(0))            # identical to the ambiguous figure
+    await db.commit()
+    assert await match_image(db, query.id) == []     # no clean references → nothing
+
+
+@pytest.mark.asyncio
+async def test_auto_apply_tags_confident_match(db):
+    raven = await TagService(db).find_or_create("Raven", TagKind.character)
+    ref = await _img(db, "l" * 64)
+    await _figure(db, ref.id, _ccip(0))
+    await _tag_image(db, ref.id, raven.id)           # single-character reference
+    query = await _img(db, "m" * 64)
+    await _figure(db, query.id, _ccip(0))            # identical → cosine 1.0
+    await db.commit()
+
+    from backend.app.tasks.ml import scheduled_ccip_auto_apply
+    assert "applied=" in scheduled_ccip_auto_apply()   # sync task, own session
+
+    rows = (await db.execute(
+        select(image_tag.c.tag_id, image_tag.c.source).where(
+            image_tag.c.image_record_id == query.id
+        )
+    )).all()
+    assert (raven.id, "ccip_auto") in [(t, s) for t, s in rows]