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

alembic/versions/0064_ccip_auto_apply.py

@@ -0,0 +1,42 @@
+"""ml_settings: CCIP auto-apply switch + threshold (#114)
+
+Confident CCIP character matches auto-tag (source='ccip_auto') on a daily sweep,
+so identity tags keep flowing without pressing a button. ON by default (opt-out,
+like head auto-apply); the high threshold (0.92, above the 0.85 suggest cut) +
+single-character references keep it safe, and every auto-tag is reversible.
+
+Revision ID: 0064
+Revises: 0063
+Create Date: 2026-06-30
+"""
+from typing import Sequence, Union
+
+import sqlalchemy as sa
+from alembic import op
+
+revision: str = "0064"
+down_revision: Union[str, None] = "0063"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.add_column(
+        "ml_settings",
+        sa.Column(
+            "ccip_auto_apply_enabled", sa.Boolean(), nullable=False,
+            server_default=sa.true(),
+        ),
+    )
+    op.add_column(
+        "ml_settings",
+        sa.Column(
+            "ccip_auto_apply_threshold", sa.Float(), nullable=False,
+            server_default="0.92",
+        ),
+    )
+
+
+def downgrade() -> None:
+    op.drop_column("ml_settings", "ccip_auto_apply_threshold")
+    op.drop_column("ml_settings", "ccip_auto_apply_enabled")