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/checkpoints.py

@@ -40,6 +40,7 @@ from typing import Any, Literal
 
 from pydantic import BaseModel, Field
 
+from artemis.runtime.cancellation import CancellationReason
 from artemis.utils.logger import get_logger
 from artemis.utils.notes import append_note_content, get_note_file_path
 from artemis.utils.plan_grammar import (
@@ -1030,7 +1031,7 @@ async def spawn_pending_checkpoints(ctx, state, anchor_step_id: str | None) -> l
                 # including failures, are never dropped), ledger-only.
                 findings.extend(harvest_run(ctx, state, old_run, allow_side_effects=False))
             else:
-                old_run.task.cancel()
+                old_run.task.cancel(CancellationReason.SUPERSEDED)
                 try:
                     await old_run.task
                 except (asyncio.CancelledError, Exception) as exc:
@@ -1088,14 +1089,16 @@ async def settle_all_checkpoints(ctx, state) -> None:
 
     timeout = float(_setting(ctx, "settlement_timeout", 120.0))
     tasks = [r.task for r in runs]
+    cancel_reason = CancellationReason.OUTER_TIMEOUT
     try:
         _done, pending = await asyncio.wait(tasks, timeout=timeout)
     except Exception as e:
         logger.error(f"Settlement wait failed: {e}")
+        cancel_reason = CancellationReason.UNKNOWN
         pending = {t for t in tasks if not t.done()}
 
     for t in pending:
-        t.cancel()
+        t.cancel(cancel_reason)
     for t in pending:
         try:
             await t