Announce expanded/collapsed state on the timeline group header (#7226)

* Announce expanded/collapsed state on the timeline group header

GroupHeaderView (the accordion-style header used for grouped state
events in the timeline) uses toggleable() combined with
clearAndSetSemantics { contentDescription = text }. The
clearAndSetSemantics block discards the state information that
toggleable() would otherwise expose, so TalkBack never announces
whether the group is currently expanded or collapsed.

Add an explicit stateDescription (two new a11y_state_expanded /
a11y_state_collapsed strings in temporary.xml) alongside the existing
contentDescription so the expanded/collapsed state is communicated to
assistive technology.

Internal note: this single-file/single-root-cause fix addresses three
separate BITV findings raised in the same accessibility audit against
this component's toggle semantics.

* Update screenshots

---------

Co-authored-by: ElementBot <android@element.io>

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/components/group/GroupHeaderView.kt

@@ -26,9 +26,11 @@ import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.clip
 import androidx.compose.ui.draw.rotate
 import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.semantics.Role
 import androidx.compose.ui.semantics.clearAndSetSemantics
 import androidx.compose.ui.semantics.contentDescription
+import androidx.compose.ui.semantics.stateDescription
 import androidx.compose.ui.unit.dp
 import io.element.android.compound.theme.ElementTheme
 import io.element.android.compound.tokens.generated.CompoundIcons
@@ -37,6 +39,7 @@ import io.element.android.libraries.designsystem.preview.PreviewsDayNight
 import io.element.android.libraries.designsystem.theme.components.Icon
 import io.element.android.libraries.designsystem.theme.components.Surface
 import io.element.android.libraries.designsystem.theme.components.Text
+import io.element.android.libraries.ui.strings.CommonStrings
 
 private val CORNER_RADIUS = 8.dp
 
@@ -52,6 +55,8 @@ fun GroupHeaderView(
     val backgroundColor = Color.Transparent
     val shape = RoundedCornerShape(CORNER_RADIUS)
 
+    val expandedStateDescription = stringResource(CommonStrings.a11y_state_expanded)
+    val collapsedStateDescription = stringResource(CommonStrings.a11y_state_collapsed)
     Box(
         modifier = modifier
             .fillMaxWidth()
@@ -62,6 +67,7 @@ fun GroupHeaderView(
             )
             .clearAndSetSemantics {
                 contentDescription = text
+                stateDescription = if (isExpanded) expandedStateDescription else collapsedStateDescription
             },
         contentAlignment = Alignment.Center
     ) {

libraries/ui-strings/src/main/res/values/temporary.xml

@@ -8,6 +8,8 @@
 <resources>
     <string name="action_mark_as_read">"Mark as read"</string>
     <string name="a11y_jump_to_unread_messages">"Jump to first unread message"</string>
+    <string name="a11y_state_expanded">"Expanded"</string>
+    <string name="a11y_state_collapsed">"Collapsed"</string>
     <string name="screen_local_network_opt_in_title">Allow access to local network</string>
     <string name="screen_local_network_opt_in_subtitle">Your homeserver is on your local network. To connect, Element needs permission to reach other devices on this network.</string>
     <string name="a11y_active">Active</string>