feat(tooling): X-Ray threshold optimizer, gallery utilities, artifact registry, docs build

Optimizer (scripts/optimizer/): replay.py runs the real C++ tracker/matcher/
scene_tracker chain over a dumped-embeddings HDF5 via sae_kpn, so a threshold
sweep never re-decodes video or re-embeds faces. optimize.py drives scipy's
differential_evolution over the knob space, with DE-level parallelism
(multiple population candidates evaluated concurrently via a ThreadPoolExecutor)
on top of per-film replay parallelism. second_score.py is the per-second X-Ray
scoring metric (TPI/FPI/FN, out-of-cast misID weighted 10x, fair recall masked
to gallery-known cast) that superseded an earlier scene-union metric.
dump_error_frames.py / dump_scene_montage.py extract annotated video frames
(bounding boxes, TPI/FPI/FN captions, onscreen-vs-offscreen split) for visual
review of a replay against ground truth. Gallery utilities: cast_restrict.py,
gallery_membership.py, fetch_missing_actors.py, reembed_gallery.py.

scripts/validation/: X-Ray ground-truth loading and provider-agnostic identity
matching (identity.py's keys_for — an actor is the union of every id we can
derive, since pipeline output and ground truth don't share one id space).

scripts/artifacts/: push/pull scripts for the Gitea generic package registry —
galleries, montage frames, and experiment data (manifests/trajectories/results)
are pushed there instead of committed, since none are needed to run the app,
only benchmarks. Versioned by git short-SHA.

scripts/docs/: MkDocs site build (build_site.sh) and the calibration-curve
comparison chart (calibration_chart.py, matplotlib, reads each gallery's
embedded calibration).

Gallery-building scripts (make_jellyfin_gallery.py, make_gallery.py,
filter_gallery.py, run_from_jellyfin.py, movienet_eval.py, movienet_prep.py,
sae_gallery.py) updated to read/write HDF5 galleries exclusively, matching the
engine-side format switch. run_from_jellyfin.py and the optimizer no longer
carry movie source paths in shared manifests (some source filenames include
scene-release tags) — resolved locally via a gitignored file-lut.json instead.

scripts/make_gallery.py

@@ -1,9 +1,9 @@
 #!/usr/bin/env python3
-"""make_gallery.py — fetch actor images for a movie and build gallery.json.
+"""make_gallery.py — fetch actor images for a movie and build gallery.h5.
 
 Fetches the cast from TMDB, downloads actor profile images, embeds them via
 the sae_embed module (SCRFD + ArcFace, same models as scene_analyze, loaded
-once), then writes gallery.json.
+once), then writes gallery.h5.
 
 Requirements:
     pip install requests Pillow
@@ -13,13 +13,13 @@ Usage:
     python scripts/make_gallery.py \\
         --tmdb-key YOUR_KEY \\
         --imdb-id tt0137523 \\
-        --output gallery.json
+        --output gallery.h5
 
     # Or directly with a TMDB movie ID:
     python scripts/make_gallery.py \\
         --tmdb-key YOUR_KEY \\
         --movie-id 550 \\
-        --output gallery.json
+        --output gallery.h5
 
     # Additional options:
     #   --build-dir build/             build dir containing sae_embed module
@@ -31,7 +31,6 @@ Get a free TMDB API key at: https://www.themoviedb.org/settings/api
 """
 
 import argparse
-import json
 import sys
 import time
 from pathlib import Path
@@ -151,7 +150,7 @@ def build_gallery(movie_id: int, key: str, embedder,
 
 def main():
     parser = argparse.ArgumentParser(
-        description="Fetch TMDB cast images and build gallery.json via sae_embed")
+        description="Fetch TMDB cast images and build gallery.h5 via sae_embed")
     parser.add_argument("--tmdb-key",  required=True,
                         help="TMDB Bearer token (API Read Access Token from themoviedb.org/settings/api)")
     group = parser.add_mutually_exclusive_group(required=True)
@@ -159,7 +158,7 @@ def main():
                         help="IMDB movie ID, e.g. tt0137523 — looked up via TMDB automatically")
     group.add_argument("--movie-id",  type=int,
                         help="TMDB movie ID (alternative to --imdb-id)")
-    parser.add_argument("--output",          required=True,  help="Output gallery.json path")
+    parser.add_argument("--output",          required=True,  help="Output gallery.h5 path")
     parser.add_argument("--build-dir",       default="build",
                         help="Build directory containing the sae_embed module (default: build)")
     parser.add_argument("--models-dir",      default="models",