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.

artemis/graph/graph.py

@@ -63,6 +63,7 @@ from artemis.graph.perception import perception_node
 from artemis.graph.state import State
 from artemis.graph.visibility import strict_state
 from artemis.llm.diagnostics import final_review_error_text
+from artemis.runtime.cancellation import CancellationReason
 from artemis.services.llm import final_review_budget
 from artemis.tools.command_tool import (
     HANG_GUIDANCE,
@@ -816,7 +817,7 @@ async def _process_plan_write(
 
             if ctx.planner_task and not ctx.planner_task.done():
                 # A newer write supersedes the in-flight validation.
-                ctx.planner_task.cancel()
+                ctx.planner_task.cancel(CancellationReason.SUPERSEDED)
 
             ctx.pending_validated_plan = content_after
             initial_goal = (