Golden gate: Linux baselines, canonical save, gate hardening (D521-D532)

Linux reference-frame set for all 21 levels and the cross-platform golden
rule (D521); golden tooling made non-destructive (D524); the gate pins a
canonical in-tree save (D529) and the PRNG seed (D532); the capture tool's
per-level re-pin bug fixed and the Linux set re-captured under the
canonical save (D530, D531); no-arg verify.sh exits non-zero. README and
docs visual/consolidation passes; the 15 MB preview gif replaced by stills.

Refs: D521 D523 D524 D525 D526 D527 D528 D529 D530 D531 D532

docs/dev/D356-SETTINGS-REGROUP-PLAN.md

@@ -5,7 +5,7 @@ this session; verification in `docs/dev/findings.md` D356 (GE_WSPROBE_RESET
 front + in-stage probes, regressions, build). Supersedes the "BOND FILE"
 section introduced in D353. Baselines: Turok PC port options (Nightdive, list
 provided by the maintainer), the PD port's `port/src/optionsmenu.c`
-(`C:\Users\james\Source\Repos\pd_port`), and plan §6 of
+(`<repos>\pd_port`), and plan §6 of
 `docs/dev/OPTIONS-MENU-PLAN.md` (the original "align with Turok" note).
 
 ## 1. Goal