feat: make map and []any config fields editable as JSON text in Android UI

Replace ReadOnlyField with JsonField composable that provides multi-line
JSON editing with real-time validation feedback. Add prettyPrint
serialization for readable display and parseToJsonElement for save,
letting parse errors propagate to the existing error snackbar.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

android/backend/config/src/main/java/io/clawdroid/backend/config/ConfigSectionDetailScreen.kt

@@ -201,7 +201,7 @@ private fun ConfigField(
         "float" -> NumberField(field, onValueChanged, KeyboardType.Decimal)
         "[]string" -> StringArrayField(field, onValueChanged)
         "directory" -> DirectoryField(field, onValueChanged, snackbarHostState)
-        "map", "[]any" -> ReadOnlyField(field)
+        "map", "[]any" -> JsonField(field, onValueChanged)
         else -> StringField(field, onValueChanged)
     }
 }
@@ -296,13 +296,26 @@ private fun StringArrayField(field: FieldState, onValueChanged: (String) -> Unit
 }
 
 @Composable
-private fun ReadOnlyField(field: FieldState) {
+private fun JsonField(field: FieldState, onValueChanged: (String) -> Unit) {
+    val jsonError = remember(field.value) {
+        if (field.value.isBlank()) null
+        else try {
+            kotlinx.serialization.json.Json.parseToJsonElement(field.value); null
+        } catch (e: Exception) {
+            e.message
+        }
+    }
+
     OutlinedTextField(
-        value = field.value.ifEmpty { "(complex value)" },
+        value = field.value,
-        onValueChange = {},
+        onValueChange = onValueChanged,
         label = { Text(field.label, color = TextSecondary) },
-        readOnly = true,
+        singleLine = false,
-        enabled = false,
+        minLines = 3,
+        isError = jsonError != null,
+        supportingText = if (jsonError != null) {
+            { Text(jsonError, color = MaterialTheme.colorScheme.error) }
+        } else null,
         colors = configFieldColors(),
         modifier = Modifier.fillMaxWidth(),
     )

android/backend/config/src/main/java/io/clawdroid/backend/config/ConfigViewModel.kt

@@ -9,6 +9,7 @@ import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.asStateFlow
 import kotlinx.coroutines.flow.update
 import kotlinx.coroutines.launch
+import kotlinx.serialization.json.Json
 import kotlinx.serialization.json.JsonArray
 import kotlinx.serialization.json.JsonElement
 import kotlinx.serialization.json.JsonNull
@@ -29,6 +30,7 @@ class ConfigViewModel(private val apiClient: ConfigApiClient) : ViewModel() {
     private var configValues: JsonObject? = null
     private var saveJob: Job? = null
     private var pendingSectionKey: String? = null
+    private val prettyJson = Json { prettyPrint = true }
 
     init {
         loadData()
@@ -193,6 +195,7 @@ class ConfigViewModel(private val apiClient: ConfigApiClient) : ViewModel() {
                     element.map { it.jsonPrimitive.contentOrNull ?: "" }.joinToString(", ")
                 } else ""
             }
+            "map", "[]any" -> prettyJson.encodeToString(JsonElement.serializer(), element)
             else -> (element as? JsonPrimitive)?.contentOrNull ?: element.toString()
         }
     }
@@ -232,6 +235,7 @@ class ConfigViewModel(private val apiClient: ConfigApiClient) : ViewModel() {
                 .filter { it.isNotEmpty() }
                 .map { JsonPrimitive(it) }
         )
+        "map", "[]any" -> prettyJson.parseToJsonElement(field.value)
         else -> JsonPrimitive(field.value)
     }
 }