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_dag.py

@@ -0,0 +1,111 @@
+"""Tests for DAG validation."""
+
+import time
+
+import pytest
+
+from ect import Payload, MemoryLedger, validate_dag, default_dag_config
+
+
+def test_validate_dag_root():
+    store = MemoryLedger()
+    payload = Payload(
+        iss="",
+        aud=[],
+        iat=0,
+        exp=0,
+        jti="jti-001",
+        exec_act="",
+        pred=[],
+        wid="wf-1",
+    )
+    validate_dag(payload, store, default_dag_config())
+
+
+def test_validate_dag_duplicate_jti():
+    store = MemoryLedger()
+    p = Payload(
+        iss="x",
+        aud=["y"],
+        iat=0,
+        exp=0,
+        jti="jti-001",
+        exec_act="a",
+        pred=[],
+        wid="wf-1",
+    )
+    store.append("dummy-jws", p)
+    payload = Payload(
+        iss="",
+        aud=[],
+        iat=0,
+        exp=0,
+        jti="jti-001",
+        exec_act="",
+        pred=[],
+        wid="wf-1",
+    )
+    with pytest.raises(ValueError, match="task ID.*already exists"):
+        validate_dag(payload, store, default_dag_config())
+
+
+def test_validate_dag_pred_exists():
+    store = MemoryLedger()
+    now = int(time.time())
+    p = Payload(
+        iss="x",
+        aud=["y"],
+        iat=now - 60,
+        exp=now + 600,
+        jti="jti-001",
+        exec_act="a",
+        pred=[],
+        wid="wf-1",
+    )
+    store.append("jws1", p)
+    payload = Payload(
+        iss="",
+        aud=[],
+        iat=now,
+        exp=now + 600,
+        jti="jti-002",
+        exec_act="b",
+        pred=["jti-001"],
+        wid="wf-1",
+    )
+    validate_dag(payload, store, default_dag_config())
+
+
+def test_validate_dag_pred_not_found():
+    store = MemoryLedger()
+    now = int(time.time())
+    payload = Payload(
+        iss="",
+        aud=[],
+        iat=now,
+        exp=now + 600,
+        jti="jti-002",
+        exec_act="",
+        pred=["jti-missing"],
+    )
+    with pytest.raises(ValueError, match="predecessor task not found"):
+        validate_dag(payload, store, default_dag_config())
+
+
+def test_validate_dag_pred_policy_rejected_requires_compensation():
+    store = MemoryLedger()
+    now = int(time.time())
+    p = Payload(
+        iss="x", aud=["y"], iat=now - 60, exp=now + 600,
+        jti="jti-rej", exec_act="a", pred=[], wid="wf-1",
+        ext={"pol": "p", "pol_decision": "rejected"},
+    )
+    store.append("jws1", p)
+    payload = Payload(
+        iss="", aud=[], iat=now, exp=now + 600,
+        jti="jti-child", exec_act="b", pred=["jti-rej"], wid="wf-1",
+    )
+    with pytest.raises(ValueError, match="compensation"):
+        validate_dag(payload, store, default_dag_config())
+    payload.ext = {"compensation_required": True}
+    validate_dag(payload, store, default_dag_config())