S00-003: Record blocked task and remediation handoff

Changes: Preserve incomplete work and blocker metadata for S00-003. This checkpoint does not mark implementation accepted.
Validation: Session ended with status blocked.
Blocker: S00-003 cannot reproduce accepted Node 24.21.0/npm 11.19.0 or install locked Stanza: host tools are 24.1.0/11.3.0, parent node_modules is absent, and normal official HTTPS retrieval fails with unresolved configured proxy.

Task: S00-003
Agent: auto-protocol-59f4d359b339
Role: protocol
Action: claim
Status: blocked

Task title: Проверить XMPP WSS/auth библиотеку

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; todo.
+- [S00-003](../tasks/S00-003.md): Проверить XMPP WSS/auth библиотеку — protocol; blocked.
 - [S00-004](../tasks/S00-004.md): Проверить browser OMEMO backend — crypto; todo.
 - [S00-005](../tasks/S00-005.md): Выбрать IndexedDB wrapper и migration policy — storage; todo.
 - [S00-006](../tasks/S00-006.md): Зафиксировать browser/reference matrix — orchestrator; todo.
@@ -24,6 +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; blocked.
 - [S00-010](../tasks/S00-010.md): Gate: Профиль и проверка стека — qa; todo.
 
 ## Граница этапа