docs: four focused findings pages (best model, gallery scope, expansion, deep dive)

Splits the rep4 write-up's key findings into their own linkable pages:
- best-model.md: calibration curves first (discriminative power, independent
  of any threshold), then F1 on the benchmark — LVFace-B Glint360K wins both.
- gallery-scope.md: whole vs. cast-restricted gallery, isolated from model and
  expansion choice — restriction wins on every axis, but isn't a shipped
  runtime feature yet.
- pose-expansion.md: the training-set expand_gallery effect, and the held-out
  replication attempt that found it doesn't reproduce (5 films, 2 models,
  after catching and fixing a replay-timeout truncation bug and a bbox
  first-match-instead-of-best-match bug in the comparison harness itself). An
  honest null result, with the methodology errors documented since they're
  exactly the kind that manufacture a false "it works!" finding.
- lvface-deep-dive.md: the winning model's held-out generalization gap, its
  two failure modes (frozen-bbox ghost tracks), and a verified case (cross-
  checked against Jellyfin's independent cast metadata) where LVFace
  correctly identified an actor that X-Ray's ground truth failed to credit.

Adds a "report-highlights" artifact-registry package (scripts/artifacts/
push_artifacts.sh, pull_artifacts.sh) for hand-picked illustrative frames that
aren't reproducible via the automated best/worst montage selection, and wires
pulling it into scripts/docs/build_site.sh.

scripts/artifacts/push_artifacts.sh

@@ -11,12 +11,16 @@
 #   scripts/artifacts/push_artifacts.sh galleries
 #   scripts/artifacts/push_artifacts.sh montage-frames
 #   scripts/artifacts/push_artifacts.sh experiment-data
-#   scripts/artifacts/push_artifacts.sh galleries montage-frames experiment-data
+#   scripts/artifacts/push_artifacts.sh report-highlights
+#   scripts/artifacts/push_artifacts.sh galleries montage-frames experiment-data report-highlights
 #
 # Package layout (owner=dtourolle, repo=scene-actor-extraction):
 #   generic/galleries/<version>/gallery_<model>.h5        (one file per model)
 #   generic/montage-frames/<version>/<film-slug>.zip      (zipped per-film frames)
 #   generic/experiment-data/<version>/experiment-data.zip (manifests/trajectories/results)
+#   generic/report-highlights/<version>/<name>.jpg        (individual, hand-picked
+#     illustrative frames referenced by docs/*.md that aren't reproducible via
+#     the automated best/worst montage selection — see scripts/docs/build_site.sh)
 # version = current git short SHA, so artifacts are traceable to the code that
 # produced them. Re-running with the same SHA overwrites that version's files.
 set -euo pipefail
@@ -95,17 +99,28 @@ push_experiment_data() {
     upload "experiment-data" "experiment-data.zip" "$zipfile"
 }
 
+push_report_highlights() {
+    echo "=== report-highlights (version ${VERSION}) ==="
+    local src="${REPO_ROOT}/experiments/results/holdout/montage/many_saints/out_of_cast_fpi/10_t003641.jpg"
+    if [ ! -f "$src" ]; then
+        echo "  [warn] $src not found, skipping" >&2
+        return
+    fi
+    upload "report-highlights" "germar_beats_xray.jpg" "$src"
+}
+
 if [ $# -eq 0 ]; then
-    echo "usage: $0 <galleries|montage-frames|experiment-data> [...]" >&2
+    echo "usage: $0 <galleries|montage-frames|experiment-data|report-highlights> [...]" >&2
     exit 1
 fi
 
 for target in "$@"; do
     case "$target" in
-        galleries)        push_galleries ;;
-        montage-frames)   push_montage_frames ;;
-        experiment-data)  push_experiment_data ;;
-        *) echo "unknown target: $target (expected galleries, montage-frames, or experiment-data)" >&2; exit 1 ;;
+        galleries)          push_galleries ;;
+        montage-frames)     push_montage_frames ;;
+        experiment-data)    push_experiment_data ;;
+        report-highlights)  push_report_highlights ;;
+        *) echo "unknown target: $target (expected galleries, montage-frames, experiment-data, or report-highlights)" >&2; exit 1 ;;
     esac
 done