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/sdk/test_agent_external_cancel.py

@@ -19,11 +19,13 @@ import asyncio
 import pytest
 
 from artemis.runtime import cancel_requests
+from artemis.runtime.cancellation import CancellationReason
 from artemis.sdk.agent import Agent
 
 
 @pytest.mark.asyncio
-async def test_external_cancel_marker_cancels_running_task(tmp_path, monkeypatch):
+@pytest.mark.parametrize("cause", [CancellationReason.USER_STOP, CancellationReason.UNKNOWN])
+async def test_external_cancel_marker_cancels_running_task(tmp_path, monkeypatch, cause):
     monkeypatch.setattr(cancel_requests, "get_temp_dir", lambda _subfolder=None: tmp_path / "c")
     monkeypatch.setenv("ARTEMIS_CANCEL_POLL_SECONDS", "0.05")
 
@@ -38,9 +40,12 @@ async def test_external_cancel_marker_cancels_running_task(tmp_path, monkeypatch
     await asyncio.sleep(0.15)
     assert not agent._current_task.done()
 
-    cancel_requests.request_cancel(session_id="sess-cancel", reason="stop from UI")
+    cancel_requests.request_cancel(
+        session_id="sess-cancel", reason="stop from UI", cancel_reason=cause
+    )
 
-    with pytest.raises(asyncio.CancelledError):
+    with pytest.raises(asyncio.CancelledError) as error:
         await asyncio.wait_for(agent._current_task, timeout=2)
+    assert error.value.args == (cause,)
     await asyncio.wait_for(watcher, timeout=2)
     assert not cancel_requests.is_cancel_requested(session_id="sess-cancel")