docs: archive the July 2026 report; new methodology for the opencv5 run

The July report (4-model ArcFace/LVFace bake-off, pre-opencv5 framework,
3-film training + held-out validation) is superseded by the opencv5 build:
single-model LVFace-B, a 6-knob DE sweep over all 9 films, flood-fill
presence, and the registry/decode fixes. Rather than overwrite it, archive
it date-suffixed and start the current report fresh.

- Rename the six July result pages to *-2026-07.md, rewrite their
  intra-archive cross-links, and add an "Archived (July 2026)" banner to each.
- mkdocs nav: current report at top, the July set under an Archive section.
- New docs/methodology.md for the opencv5 run: corrects the withdrawn
  anneal_sec/extinction_sec presence bridging (windows are now
  [first_seen, last_seen], AR-012/013), documents the two presence modes
  (track_extent / flood), and records that every eval scores all 9 films.

The current experiment log (model-bakeoff.md) and Home rewrite land once
the DE sweep converges and the final optimum is known.

docs/gallery-scope-2026-07.md

@@ -0,0 +1,71 @@
+> **Archived (July 2026).** This report covers the pre-opencv5 framework and the 4-model ArcFace/LVFace bake-off. It is superseded by the current [experiment log](model-bakeoff.md) for the opencv5 build. Kept for provenance; the numbers here are historical.
+
+# Whole gallery vs. cast-restricted gallery
+
+Two ways to run the matcher. Full mode scores every detected face against
+the entire 2418-actor gallery. Restricted mode pre-filters each film's
+gallery down to just its Jellyfin-credited cast (typically around 15
+top-billed actors) before the matcher runs.
+
+## Result
+
+Averaged across the 3 compared models (r50 excluded, see
+[the full experiment log](model-bakeoff-2026-07.md)) and both expansion settings, on
+the 4 training films:
+
+| scope | F1 | P | R | total misID |
+|---|---|---|---|---|
+| full | 71.1% | 89.6% | 59.6% | 1121 |
+| restricted | 75.9% | 90.4% | 65.6% | 299 |
+
+Restriction improves every metric at once, not a precision/recall trade:
++4.8pp F1, +6.0pp recall, roughly a quarter the total misIDs. Fewer
+candidates in the matcher's search space means fewer opportunities for a
+lookalike false match, and the recall gain shows this does not cost real
+detections.
+
+Every model's best-scoring combo in the training matrix uses the
+restricted gallery:
+
+![All combos ranked by training-set F1, filled dots are restricted](assets/images/rep4_matrix_f1.png)
+
+See [the full experiment log](model-bakeoff-2026-07.md) for the complete table. One
+combo reaches zero true out-of-cast misidentifications,
+`arcface_w600k_mbf_restricted_exp` (F1 76.2%), and it is a restricted one,
+consistent with restriction, not expansion, being what suppresses cross-film
+confusions.
+
+The restriction effect (+4.8pp averaged across models) is larger than the
+model-choice effect: LVFace beats r18 by 6.2pp in full mode but beats mbf by
+3.3pp. Restriction is the single strongest lever in the matrix.
+
+## Why this is not the shipped default
+
+Cast restriction is implemented today only as an offline optimizer
+technique
+([`scripts/optimizer/cast_restrict.py`](https://REPOLINK/scripts/optimizer/cast_restrict.py)):
+it pre-builds a filtered gallery file per film using Jellyfin's cast list
+before the benchmark calls the matcher. There is no runtime "restrict to
+this title's credited cast" switch in the shipped application;
+`scene_analyze` always matches against whatever single gallery file it is
+given.
+
+Building this as a real feature requires:
+
+- A live Jellyfin cast lookup at analysis time. The title is already known,
+  and [`scripts/run_from_jellyfin.py`](https://REPOLINK/scripts/run_from_jellyfin.py)
+  already performs this lookup for its own `filter_gallery`-based
+  restriction path; it is not wired into `scene_analyze` as a first-class
+  option.
+- A decision on the fallback case: what happens to a real, uncredited
+  cameo (see the Germar Terrell Gardner and Talia Balsam cases in the
+  [LVFace deep dive](lvface-deep-dive-2026-07.md#where-lvface-beat-x-ray)) if the
+  restricted gallery never includes them at all.
+- Regenerating the restricted-gallery cache whenever a title's Jellyfin
+  cast list changes.
+
+The shipped [`src/config.hpp`](https://REPOLINK/src/config.hpp) defaults use
+the full-mode winner (`LVFace-B_Glint360K_full_exp`, F1 75.3% training,
+67.4% held-out macro) rather than the higher-scoring `restricted_exp`
+(78.3%), because 78.3% describes a capability the application does not
+have yet.