S00-020: Approve pinned Linux XMPP toolchain restoration

Changes: Accept S00-020 with independent QA evidence and handoff; refresh scoped runtime/cache result paths after fresh retrieval and installation.
Validation: verify.py passed official HTTPS checksum, Node 24.21.0/npm 11.19.0, isolated strict npm ci and Stanza import. Independent archive/input/eight-version/strict-setting assertions, tasks.py validate and diff/scope checks passed. Browser/WSS and product readiness remain untested.

Task: S00-020
Agent: auto-qa-9e1e289654ba
Role: qa
Action: review
Status: done

Task title: Restore access to the pinned Linux XMPP experiment toolchain

planning/stages/S00.md

@@ -8,7 +8,7 @@
 
 - [S00-001](../tasks/S00-001.md): Утвердить Web-профиль — orchestrator; done.
 - [S00-002](../tasks/S00-002.md): Выбрать framework и build runtime — orchestrator; done.
-- [S00-003](../tasks/S00-003.md): Проверить XMPP WSS/auth библиотеку — protocol; blocked.
+- [S00-003](../tasks/S00-003.md): Проверить XMPP WSS/auth библиотеку — protocol; todo.
 - [S00-004](../tasks/S00-004.md): Проверить browser OMEMO backend — crypto; blocked.
 - [S00-005](../tasks/S00-005.md): Выбрать IndexedDB wrapper и migration policy — storage; blocked.
 - [S00-006](../tasks/S00-006.md): Зафиксировать browser/reference matrix — orchestrator; todo.
@@ -24,7 +24,7 @@
 - [S00-017](../tasks/S00-017.md): Establish fail-closed SCRAM server-final validation — protocol; done.
 - [S00-018](../tasks/S00-018.md): Validate bounded standalone XML ingress for the XMPP candidate — protocol; done.
 - [S00-019](../tasks/S00-019.md): Validate browser-compatible SCRAM-SHA-512 through a public mechanism API — crypto; done.
-- [S00-020](../tasks/S00-020.md): Restore access to the pinned Linux XMPP experiment toolchain — ci-cd; review.
+- [S00-020](../tasks/S00-020.md): Restore access to the pinned Linux XMPP experiment toolchain — ci-cd; done.
 - [S00-021](../tasks/S00-021.md): Устранить прерывание: Проверить browser OMEMO backend — crypto; done.
 - [S00-022](../tasks/S00-022.md): Confirm or source a verified browser/WASM-capable OMEMO2 backend for the Web client endpoint — crypto; blocked.
 - [S00-023](../tasks/S00-023.md): Устранить прерывание: Выбрать IndexedDB wrapper и migration policy — storage; blocked.