feat(cli): add kanban swarm topology helper

Salvages #26791 by @Niraven. Adds 'hermes kanban swarm' to create a
durable Kanban Swarm v1 graph: a completed root/blackboard card,
parallel worker cards, a verifier gated on all workers, and a
synthesizer gated on the verifier. Stores shared swarm blackboard
updates as structured JSON comments on the root card.

Self-contained: new hermes_cli/kanban_swarm.py module + CLI wiring +
unit tests.

tests/hermes_cli/test_kanban_swarm.py

@@ -0,0 +1,118 @@
+import json
+
+from hermes_cli import kanban_db as kb
+from hermes_cli.kanban_swarm import (
+    SwarmWorkerSpec,
+    create_swarm,
+    latest_blackboard,
+    post_blackboard_update,
+)
+
+
+def test_create_swarm_builds_parallel_workers_verifier_and_synthesizer(tmp_path):
+    conn = kb.connect(tmp_path / "kanban.db")
+    try:
+        created = create_swarm(
+            conn,
+            goal="Map the target market and produce a decision memo.",
+            workers=[
+                SwarmWorkerSpec(profile="researcher-a", title="Market scan", body="Find competitors"),
+                SwarmWorkerSpec(profile="researcher-b", title="Customer scan", body="Find customer pains"),
+            ],
+            verifier_assignee="reviewer",
+            synthesizer_assignee="writer",
+            tenant="intel",
+            created_by="orchestrator",
+        )
+
+        root = kb.get_task(conn, created.root_id)
+        workers = [kb.get_task(conn, tid) for tid in created.worker_ids]
+        verifier = kb.get_task(conn, created.verifier_id)
+        synthesizer = kb.get_task(conn, created.synthesizer_id)
+
+        assert root.status == "done"
+        assert root.assignee == "orchestrator"
+        assert [task.status for task in workers] == ["ready", "ready"]
+        assert [task.assignee for task in workers] == ["researcher-a", "researcher-b"]
+        assert verifier.status == "todo"
+        assert synthesizer.status == "todo"
+        assert set(kb.parent_ids(conn, created.verifier_id)) == set(created.worker_ids)
+        assert kb.parent_ids(conn, created.synthesizer_id) == [created.verifier_id]
+        assert all(created.root_id in (task.body or "") for task in workers)
+    finally:
+        conn.close()
+
+
+def test_swarm_blackboard_merges_structured_updates(tmp_path):
+    conn = kb.connect(tmp_path / "kanban.db")
+    try:
+        created = create_swarm(
+            conn,
+            goal="Collect evidence.",
+            workers=[SwarmWorkerSpec(profile="researcher", title="Evidence", body="Find proof")],
+            verifier_assignee="reviewer",
+            synthesizer_assignee="writer",
+        )
+
+        post_blackboard_update(
+            conn,
+            created.root_id,
+            author="researcher",
+            key="sources",
+            value=["https://example.com/a"],
+        )
+        post_blackboard_update(
+            conn,
+            created.root_id,
+            author="reviewer",
+            key="risks",
+            value={"missing_primary_source": True},
+        )
+
+        board = latest_blackboard(conn, created.root_id)
+        assert board["sources"] == ["https://example.com/a"]
+        assert board["risks"] == {"missing_primary_source": True}
+        assert board["_authors"]["sources"] == "researcher"
+    finally:
+        conn.close()
+
+
+def test_swarm_verifier_and_synthesis_are_dependency_gated(tmp_path):
+    conn = kb.connect(tmp_path / "kanban.db")
+    try:
+        created = create_swarm(
+            conn,
+            goal="Research two branches then verify and synthesize.",
+            workers=[
+                SwarmWorkerSpec(profile="a", title="Branch A", body="A"),
+                SwarmWorkerSpec(profile="b", title="Branch B", body="B"),
+            ],
+            verifier_assignee="reviewer",
+            synthesizer_assignee="writer",
+        )
+
+        kb.complete_task(
+            conn,
+            created.worker_ids[0],
+            summary="A done",
+            metadata={"confidence": 0.8},
+        )
+        kb.recompute_ready(conn)
+        assert kb.get_task(conn, created.verifier_id).status == "todo"
+        assert kb.get_task(conn, created.synthesizer_id).status == "todo"
+
+        kb.complete_task(conn, created.worker_ids[1], summary="B done")
+        kb.recompute_ready(conn)
+        assert kb.get_task(conn, created.verifier_id).status == "ready"
+        assert kb.get_task(conn, created.synthesizer_id).status == "todo"
+
+        kb.complete_task(
+            conn,
+            created.verifier_id,
+            summary="Verified both branches",
+            metadata={"gate": "pass"},
+        )
+        kb.recompute_ready(conn)
+        assert kb.get_task(conn, created.synthesizer_id).status == "ready"
+    finally:
+        conn.close()