S00-004: Record blocked task and remediation handoff

Changes: Preserve incomplete work and blocker metadata for S00-004. This checkpoint does not mark implementation accepted.
Validation: Session ended with status blocked.
Blocker: Agent timed out; process terminated before escalation

Task: S00-004
Agent: auto-crypto-8bf3dcf711b9
Role: crypto
Action: claim
Status: blocked

Task title: Проверить browser OMEMO backend

state/blockers/S00-021.md

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+# Blocker S00-021
+
+- Original task: S00-004
+- Root task: S00-004
+- Reporter: auto-crypto-8bf3dcf711b9
+- Role: crypto
+- Original owner: auto-crypto-8bf3dcf711b9
+- Waits for user/external condition: False
+
+## Cause
+
+Agent timed out; process terminated before escalation
+
+## One remediation outcome
+
+Устранить одну указанную причину прерывания и доказать готовность исходной задачи к новому запуску; не выполнять соседние задачи.
+
+## Evidence / reproduction
+
+See original handoff and task evidence.
+
+The reporting agent must stop now. A new agent implements only S00-021.