Fix accessibility: announce checked/unchecked state for invite user rows (#6407)

Replace clickable(role = Role.Checkbox) with toggleable(value = checked, role =
Role.Checkbox) so TalkBack can announce the current state and state changes.
Set the inner Checkbox.onCheckedChange = null to make it a purely visual
indicator, avoiding duplicate accessibility focus on the same control.

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

libraries/matrixui/src/main/kotlin/io/element/android/libraries/matrix/ui/components/CheckableUserRow.kt

@@ -8,12 +8,12 @@
 
 package io.element.android.libraries.matrix.ui.components
 
-import androidx.compose.foundation.clickable
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.Spacer
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.width
+import androidx.compose.foundation.selection.toggleable
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.Immutable
 import androidx.compose.ui.Alignment
@@ -39,8 +39,8 @@ fun CheckableUserRow(
     Row(
         modifier = modifier
             .fillMaxWidth()
-            .clickable(role = Role.Checkbox, enabled = enabled) {
+            .toggleable(value = checked, role = Role.Checkbox, enabled = enabled) {
-                onCheckedChange(!checked)
+                onCheckedChange(it)
             },
         verticalAlignment = Alignment.CenterVertically,
     ) {
@@ -65,7 +65,7 @@ fun CheckableUserRow(
             }
         }
         Checkbox(
-            onCheckedChange = onCheckedChange,
+            onCheckedChange = null,
             checked = checked,
             enabled = enabled,
         )