feat(wip): soft title tier — sketch/doodle vocab + ring-loud audit (#1474)

Extends WIP title-tagging to lower-precision cues (sketch/doodle/scribble) safely.

- wip_title.py: soft matcher (word-anchored; sketchbook/kadoodle don't trip it);
  WIP_TITLE_SOFT_SOURCE + soft SQL prefilter; apply_wip_image_tags takes a source arg.
- training_data._AUTO_SOURCES += 'wip_title_soft' → the soft tier is PROVISIONAL and
  never trains the wip head (a finished "sketch" can't pollute it). Only the hard
  tier (wip_title) + manual train.
- ImportSettings.wip_soft_title_tagging_enabled (OFF by default, opt-in). Migration 0087.
- importer: hard tier wins, soft is the fallback (source wip_title_soft).
- backfill: refactored into a shared _backfill_wip_tier; hard always, soft when enabled.
- heads.soft_wip_conflict_audit + daily beat: score soft-tagged images against content
  heads, flag ring-loud ones (PresentationReview mode=process) for the review strip —
  the operator's "measure if they got falsely tagged" safety.
- api settings toggle; ImportFiltersForm soft toggle.
- tests: soft matcher pos/neg; soft source not a training positive; audit flags
  ring-loud + spares quiet.

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

backend/app/services/importer.py

@@ -47,7 +47,14 @@ from .attachment_store import AttachmentStore
 from .audits import single_color
 from .link_extract import extract_external_links
 from .thumbnailer import Thumbnailer
-from .wip_title import apply_wip_image_tags, matches_wip_title, resolve_wip_tag_id
+from .wip_title import (
+    WIP_TITLE_SOFT_SOURCE,
+    WIP_TITLE_SOURCE,
+    apply_wip_image_tags,
+    matches_soft_wip_title,
+    matches_wip_title,
+    resolve_wip_tag_id,
+)
 
 log = logging.getLogger(__name__)
 
@@ -999,7 +1006,9 @@ class Importer:
         removal sticks. The existing catalogue is covered separately by the
         operator-triggered backfill sweep. Gated by the settings toggle, and
         best-effort: any failure is logged, never allowed to fail the import."""
-        if not self.settings.wip_title_tagging_enabled:
+        hard_on = self.settings.wip_title_tagging_enabled
+        soft_on = self.settings.wip_soft_title_tagging_enabled
+        if not (hard_on or soft_on):
             return
         if record.primary_post_id is None:
             return
@@ -1007,13 +1016,22 @@ class Importer:
             title = self.session.execute(
                 select(Post.post_title).where(Post.id == record.primary_post_id)
             ).scalar_one_or_none()
-            if not matches_wip_title(title):
+            # HARD tier ("WIP"/"work in progress") wins — higher precision, and it
+            # trains the head; SOFT (sketch/doodle, #1474) is the provisional fallback
+            # that never trains (source wip_title_soft).
+            if hard_on and matches_wip_title(title):
+                source = WIP_TITLE_SOURCE
+            elif soft_on and matches_soft_wip_title(title):
+                source = WIP_TITLE_SOFT_SOURCE
+            else:
                 return
             if self._wip_tag_id is _UNSET:
                 self._wip_tag_id = resolve_wip_tag_id(self.session)
             if self._wip_tag_id is None:
                 return
-            apply_wip_image_tags(self.session, [record.id], self._wip_tag_id)
+            apply_wip_image_tags(
+                self.session, [record.id], self._wip_tag_id, source=source
+            )
         except Exception as exc:  # noqa: BLE001 — a tag must never fail an import
             log.warning(
                 "wip-title auto-tag failed for image %s: %s", record.id, exc