feat(perception): surface accessibility interaction state on UI-tree elements

SceneElement gains enabled/clickable/selected/checked/focused (bool | None),
populated from the literal attributes Appium's XCUITest and UiAutomator2
page_source already emit (iOS: enabled only; Android: all five). None means
"not reported by this platform", not false. to_dict() omits unset fields to
keep the LLM-facing scene JSON compact; planner_prompts.py documents the new
fields so the AI planner knows how to use them (e.g. don't tap disabled
elements, use selected/checked to judge whether a toggle already matches the
goal).

perception/ui_parser.py

@@ -2,12 +2,19 @@ from __future__ import annotations
 
 import re
 import xml.etree.ElementTree as ET
+from dataclasses import replace
 from typing import Any
 
 from core.models import Bounds, SceneElement
 
 _ANDROID_BOUNDS = re.compile(r"\[(?P<x1>-?\d+),(?P<y1>-?\d+)\]\[(?P<x2>-?\d+),(?P<y2>-?\d+)\]")
 
+# Accessibility interaction-state attributes, as literally emitted by
+# WDA/XCUITest page_source (enabled) and Appium UiAutomator2 page_source
+# (enabled, clickable, selected, checked, focused). iOS page_source does not
+# emit selected/checked/focused/clickable, so those stay None for iOS trees.
+_STATE_ATTR_KEYS = ("enabled", "clickable", "selected", "checked", "focused")
+
 
 def parse_ui_tree(raw_tree: Any) -> list[SceneElement]:
     if raw_tree is None:
@@ -44,6 +51,7 @@ def _parse_xml(raw_tree: str) -> list[SceneElement]:
                 bounds=bounds,
                 confidence=1.0,
                 source="ui",
+                **_state_from_attrs(node.attrib),
             )
         )
     return _with_stable_ids(elements, "ui")
@@ -65,6 +73,7 @@ def _parse_dict_node(node: dict[str, Any], elements: list[SceneElement]) -> None
                 bounds=bounds,
                 confidence=1.0,
                 source="ui",
+                **_state_from_attrs(attrs),
             )
         )
     for child in children:
@@ -74,14 +83,7 @@ def _parse_dict_node(node: dict[str, Any], elements: list[SceneElement]) -> None
 
 def _with_stable_ids(elements: list[SceneElement], prefix: str) -> list[SceneElement]:
     return [
-        SceneElement(
-            id=element.id or f"{prefix}-{index:03d}",
-            type=element.type,
-            text=element.text,
-            bounds=element.bounds,
-            confidence=element.confidence,
-            source=element.source,
-        )
+        element if element.id else replace(element, id=f"{prefix}-{index:03d}")
         for index, element in enumerate(elements)
     ]
 
@@ -122,6 +124,23 @@ def _text_from_attrs(attrs: dict[str, Any]) -> str | None:
     return None
 
 
+def _state_from_attrs(attrs: dict[str, Any]) -> dict[str, bool | None]:
+    return {key: _parse_bool(attrs.get(key)) for key in _STATE_ATTR_KEYS}
+
+
+def _parse_bool(value: Any) -> bool | None:
+    if isinstance(value, bool):
+        return value
+    if value is None:
+        return None
+    text = str(value).strip().lower()
+    if text in ("true", "1", "yes"):
+        return True
+    if text in ("false", "0", "no"):
+        return False
+    return None
+
+
 def _normalize_type(raw_type: str, attrs: dict[str, Any]) -> str:
     candidate = (
         attrs.get("role")