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/utils/action_target.py

@@ -0,0 +1,26 @@
+"""Freeze action identity against its decision-time observation."""
+
+import hashlib
+import json
+from pathlib import Path
+
+
+def observation_anchor(state, elements: list[dict] | None = None) -> dict:
+    image = getattr(state, "latest_screenshot", None)
+    image_name = Path(image).stem if isinstance(image, str) else None
+    tree = elements if elements is not None else getattr(state, "indexed_elements", None)
+    tree = tree if isinstance(tree, list) else []
+    signature = json.dumps([image_name, tree], sort_keys=True, ensure_ascii=False, default=str)
+    return {
+        "target_image_name": image_name,
+        "target_snapshot_id": hashlib.sha256(signature.encode()).hexdigest()[:24],
+    }
+
+
+def element_semantics(element: dict, index: int) -> dict:
+    """Copy evidence; no live element/index lookup is allowed after dispatch."""
+    result = {"target_index": index}
+    for key in ("editable", "input_value_state", "hint", "showing_hint", "focused", "is_hint"):
+        if key in element:
+            result[f"target_{key}"] = element[key]
+    return result