feat: ACT/ECT strategy, package restructure, draft -01/-02 prep

Strategic work for IETF submission of draft-nennemann-act-01 and
draft-nennemann-wimse-ect-02:

Package restructure:
- move ACT and ECT refimpls to workspace/packages/{act,ect}/
- ietf-act and ietf-ect distribution names (sibling packages)
- cross-spec interop test plan (INTEROP-TEST-PLAN.md)

ACT draft -01 revisions:
- rename 'par' claim to 'pred' (align with ECT)
- rename 'Agent Compact Token' to 'Agent Context Token' (semantic
  alignment with ECT family)
- add Applicability section (MCP, OpenAI, LangGraph, A2A, CrewAI)
- add DAG vs Linear Delegation Chains section (differentiator vs
  txn-tokens-for-agents actchain, Agentic JWT, AIP/IBCTs)
- add Related Work: AIP, SentinelAgent, Agentic JWT, txn-tokens-for-agents,
  HDP, SCITT-AI-agent-execution
- pin SCITT arch to -22, note AUTH48 status

Outreach drafts:
- Emirdag liaison email (SCITT-AI coordination)
- OAuth ML response on txn-tokens-for-agents-06

Strategy document:
- STRATEGY.md with phased action plan, risk register, timeline

Submodule:
- update workspace/drafts/ietf-wimse-ect pointer to -02 commit

workspace/packages/ect/tests/test_jti_cache.py

@@ -0,0 +1,40 @@
+"""Tests for JTI replay cache."""
+
+import time
+
+import pytest
+
+from ect import new_jti_cache
+
+
+def test_jti_cache_seen_and_add():
+    cache = new_jti_cache(10, 60)
+    assert cache.seen("jti-1") is False
+    cache.add("jti-1")
+    assert cache.seen("jti-1") is True
+    assert cache.seen("jti-2") is False
+    cache.add("jti-2")
+    assert cache.seen("jti-2") is True
+
+
+def test_jti_cache_expiry():
+    cache = new_jti_cache(10, 1)  # 1 second TTL
+    cache.add("jti-1")
+    assert cache.seen("jti-1") is True
+    time.sleep(1.1)
+    assert cache.seen("jti-1") is False
+
+
+def test_jti_cache_max_size_eviction():
+    cache = new_jti_cache(2, 60)
+    cache.add("jti-1")
+    cache.add("jti-2")
+    cache.add("jti-3")
+    assert cache.seen("jti-3") is True
+
+
+def test_jti_cache_add_when_already_present():
+    cache = new_jti_cache(2, 60)
+    cache.add("jti-1")
+    cache.add("jti-1")
+    assert cache.seen("jti-1") is True