feat: prepare 2.2.0 with UI and execution fixes

Add dark theme, richer Markdown and readable plugin results.
Improve Android input evidence, response integrity and diagnostics.
Unify lifecycle, guidance receipts and evidence sources across clients.
Keep direct action dispatch without an added AI quota approval layer.
Align version metadata at 2.2.0 and bundle Helper 1.2.2.

Validation: 3063 backend tests before the version bump; 44 after.
Frontend: 317 tests and production build passed.

tests/unit/runtime/test_cancel_requests.py

@@ -19,6 +19,7 @@ import time
 import pytest
 
 from artemis.runtime import cancel_requests as cr
+from artemis.runtime.cancellation import CancellationReason
 
 
 @pytest.fixture(autouse=True)
@@ -91,3 +92,27 @@ async def test_watch_delivers_once_and_clears_marker():
     assert await asyncio.wait_for(watcher, timeout=2) is True
     assert delivered == [1]
     assert not cr.is_cancel_requested(session_id="w-1")
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize("cause", [CancellationReason.USER_STOP, CancellationReason.UNKNOWN])
+async def test_watch_forwards_only_the_structured_cause(cause):
+    path = cr.request_cancel(
+        session_id="with-reason", reason="private stop details", cancel_reason=cause
+    )[0]
+    delivered = []
+    assert await cr.watch_for_cancel_request(
+        delivered.append, session_id="with-reason", pid=0, pass_reason=True
+    )
+    assert delivered == [cause]
+    assert not path.exists()
+
+
+def test_legacy_or_unrecognized_marker_reasons_remain_unknown():
+    path = cr.request_cancel(session_id="legacy", reason="stop from UI")[0]
+    payload = json.loads(path.read_text(encoding="utf-8"))
+    for value in [None, "private user instruction", ["user_stop"]]:
+        payload["cancel_reason"] = value
+        path.write_text(json.dumps(payload), encoding="utf-8")
+        assert cr.get_cancel_reason(session_id="legacy") is CancellationReason.UNKNOWN
+        assert cr.is_cancel_requested(session_id="legacy")