refactor(bench): SuperHero replaces Road to Bali as the reference film

Bali was chosen because the TRECVID DVU set ships character mugshots, but
its reference crops are unusable at scale: median detected face 27 px
against a 69 px maximum, so every reference was upscaled 4x or more past
what the embedder was trained for (AR-011). A 66 px floor left 2 of 69
references; no threshold exists that both keeps the faces in distribution
and leaves enough of them to calibrate.

SuperHero is 69 px median and 241 px max. Its gallery builds at a 66 px
floor with 14 references over 5 characters, and calibrates on its own
(a=15.2867 b=-4.98633, 100% train accuracy) instead of borrowing constants.

Measured on the fused 17-minute film, one stream rather than per-scene
clips so presence windows cross real scene boundaries as SR-002 intends:
precision 1.00, recall 0.65, F1 0.79 — 13 true positives, 0 false
positives, 7 misses. Every out-of-gallery character was declined rather
than forced onto a nearest match. The misses are the short scenes (14 s,
38 s, 27 s), consistent with per-track accumulation needing sightings.

- build_gallery gains --min-face-px, filtering the *detected face* rather
  than the crop. The DVU images are scene crops, not mugshots, so crop
  dimensions say nothing about face scale. A poisoned reference is
  permanent in a way a bad frame is not: it corrupts every future match
  against that identity.
- scripts/fetch_dvu.sh fetches mugshots, scene graphs and segmentation for
  any DVU film. NIST names the same film three different ways, so KG_DIR
  and KG_FILE are overridable rather than derived. This exists as a script
  because the first copy of this data was assembled ad hoc in /tmp and was
  lost with it, taking the working gallery along.
- Replay fixtures move to the artifact registry: push/pull_artifacts.sh
  gain a replay-fixtures target, and tests/fixtures/dumps/.gitignore keeps
  them out of git. superhero.h5 is ~9 MB and regenerating it needs the
  film, the models and a GPU — none of which CI has. The gallery ships
  with the dumps, since a dump only replays against the gallery it was
  produced with.
- AR-012 and AR-013 coverage is ported onto the new fixture rather than
  dropped with the Bali cases: 12369 assertions, up from 7991, since the
  film is an order of magnitude larger than the clips.

Suite: 15679 assertions, 101 test cases.

TRACES: AR-011, AR-012, AR-013 | VR-001, VR-005 | SR-002

scripts/make_fixtures.sh

@@ -19,13 +19,16 @@
 # on a full channel (AR-004). Before that fix the same command produced
 # different dumps run to run, since what got dropped depended on timing.
 #
-# Source: bali/ — Road to Bali (1952), public domain. That matters: derived
+# Source: hero/ — SuperHero, from the TRECVID DVU development set. Chosen over
+# SuperHero on face scale: Bali reference crops had a median detected face of
+# 27 px against a 69 px maximum, so every reference was upscaled far past what
+# the embedder was trained for. SuperHero is 69 px median, 241 px max. That matters: derived
 # fixtures can be committed, where anything cut from a copyrighted title could
 # not live in the repository at all.
 set -euo pipefail
 
 REPO="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
-CLIPS="${CLIPS:-$REPO/../bali}"
+CLIPS="${CLIPS:-$REPO/../hero}"
 GALLERY="${GALLERY:-$REPO/gallery_lvface.h5}"
 BIN="${BIN:-$REPO/build/scene_analyze}"
 OUT="$REPO/tests/fixtures/dumps"
@@ -33,8 +36,12 @@ OUT="$REPO/tests/fixtures/dumps"
 # Pinned. Changing either invalidates every committed fixture.
 #   fps 5      — 1 fps over a 77 s clip is 77 frames, too thin to exercise an
 #                extinction window measured in tens of seconds.
-#   min-face   — 32 px, the VR-005 measured floor (98.1% TPI). The corpus is
-#                480x360, so a stricter value would reject most faces present.
+#   min-face   — 32 px. This is a *fixture* setting, deliberately below AR-002's
+#                production floor of 40 px (VR-013, measured end to end): the
+#                corpus is 480x360, where faces run 40-80 px, so pinning at 40
+#                would thin the dumps for reasons unrelated to what they test.
+#                32 px is where VR-005 still shows 98.1% TPI, so the faces kept
+#                are identifiable; it is not the threshold the pipeline ships.
 FPS=5
 MIN_FACE_PX=32
 
@@ -44,12 +51,12 @@ MIN_FACE_PX=32
 
 mkdir -p "$OUT"
 
-for clip in "$CLIPS"/Road_To_Bali-*.webm; do
+for clip in "$CLIPS"/SuperHero-*.webm; do
     n="$(basename "$clip" .webm)"; n="${n##*-}"
-    echo "── bali_$n"
+    echo "── superhero_$n"
     "$BIN" --movie "$clip" --gallery "$GALLERY" \
            --fps "$FPS" --min-face-px "$MIN_FACE_PX" \
-           --dump-embeddings "$OUT/bali_$n.h5" \
+           --dump-embeddings "$OUT/superhero_$n.h5" \
            --output /dev/null 2>&1 | grep -E "wrote|dropped" || true
 done