docs(rust): stage 6 of the last fixes — protocol 14 released, the cutover landed

PLAN_LAST_FIXES gains §8.1, stage 6 as built: the merge order, the five
releases (website main 6890a74, Rust-Plugins v0.3.0, Rust-Link v0.3.0,
installer v0.8.0, Module-Rust v0.5.0) and bundle 2026.10.22, the one
harmless red release run, the installer and the egg proved over scratch
roots, the rigs on the released files, and the walk site on v0.5.0. Its
status, §7 and §8's table follow. PLAN_REDESIGNS, rust-link/INSTALL.md and
STEAM_SIGNIN.md now name protocol 14 and the cutover as shipped.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E14m6SuuY6i1vASFeGDBeY

website/STEAM_SIGNIN.md

@@ -1,7 +1,8 @@
 # Sign in with Steam — plan
 
 > **Status: plan, written 2026-10-14; its questions answered 2026-10-19 (§7, D392–D396); built 2026-10-19 on
-> the website's and Module-Rust's `edge` (§8).** It ships in the cutover in progress (the org lead, 2026-10-19).
+> the website's and Module-Rust's `edge` (§8), and shipped to `main` in the cutover on 2026-10-22** (website#220,
+> MODULE_API 1.17.0; Module-Rust v0.5.0).
 > The live walk with a real Steam account (§6) is owed.
 > It is the website's own plan for Steam sign-in, as Rust's
 > [`PLAN_FIXES.md`](../modules/rust/PLAN_FIXES.md) D171 set out (§4.8 there), and it is on the roadmap as the
@@ -146,7 +147,7 @@ The org lead answered Q1–Q4 and ruled on the case Q1 and Q2 raised together. T
 
 ## 8. Built (2026-10-19)
 
-On the `edge` branches of the cutover in progress, as §4 laid out:
+On the `edge` branches of the cutover, which reached `main` on 2026-10-22, as §4 laid out:
 
 - **Core (`website`):** `steam.provider.js` does §3's checks and the `check_authentication` POST;
   `registry.js` makes Steam a built-in (priority 3) whose only requirement is the Web API key;