fix: resolve code review issues — schema mismatch, test fixes, pop-out render

- Fix a2ui-format.md schema to match renderer: rename 'options' → 'filters' in
  filters block, replace 'active: boolean' with 'value: string' in filter options,
  update form select options from string[] to {label, value}[] objects (Critical #1)
- Fix 3 failing tests in test_researcher_agent.sh to use @mention paths without .md
  extension (Important #2)
- Complete pop-out feature in VisualBlock.handlePopOut() by posting render message
  to popup window after 500ms initialization delay (Important #3)
- Update test_context_files.sh to match new a2ui-format.md schema (filters array
  key check, value field check)

bundle/context/a2ui-format.md

@@ -28,20 +28,20 @@ Renders a row of toggle chips. Use for quick category or attribute filtering.
 ```a2ui
 {
   "type": "filters",
-  "options": [
-    { "label": "Toyota", "active": true },
-    { "label": "Honda", "active": false },
-    { "label": "Hyundai", "active": false },
-    { "label": "Under $5K", "active": false }
+  "filters": [
+    { "label": "Toyota", "value": "toyota" },
+    { "label": "Honda", "value": "honda" },
+    { "label": "Hyundai", "value": "hyundai" },
+    { "label": "Under $5K", "value": "under_5k" }
   ]
 }
 ```
 
 | Field | Type | Description |
 |-------|------|-------------|
-| `options` | array | List of filter chips |
-| `options[].label` | string | Display text for the chip |
-| `options[].active` | boolean | Whether the chip is pre-selected |
+| `filters` | array | List of filter chips |
+| `filters[].label` | string | Display text for the chip |
+| `filters[].value` | string | Machine-readable identifier for the chip |
 
 ---
 
@@ -113,7 +113,11 @@ configure a follow-up action.
       "name": "fuel_type",
       "type": "select",
       "label": "Fuel Type",
-      "options": ["hybrid", "electric", "any"]
+      "options": [
+        { "label": "Hybrid", "value": "hybrid" },
+        { "label": "Electric", "value": "electric" },
+        { "label": "Any", "value": "any" }
+      ]
     }
   ],
   "submitLabel": "Search"
@@ -127,7 +131,7 @@ configure a follow-up action.
 | `fields[].type` | string | `"number"`, `"text"`, `"select"` |
 | `fields[].label` | string | Human-readable label |
 | `fields[].value` | any | Default value (for `number`/`text` fields) |
-| `fields[].options` | string[] | Choice list (for `select` fields) |
+| `fields[].options` | `{label, value}[]` | Choice list (for `select` fields); each item has a display `label` and machine-readable `value` |
 | `submitLabel` | string | Text on the submit button |
 
 ---