Add RTL text support, ported onto the post-rewrite development branch

Reimplements PR BlueBubblesApp#3049's right-to-left support (Farsi/Arabic/Hebrew) on top
of `development` instead of the old master-based branch, per jjoelj's note.

- getTextDirection(): first-strong (UAX#9) direction detection over runes
  (lib/helpers/ui/text_direction_helpers.dart); applied as the textDirection
  of message bubbles, reply bubbles, conversation-list title/subtitle, and the
  send animation (no LTR flash on send).
- Compose + subject TextFields wrapped in TextDirectionBuilder so they flip
  direction live but rebuild only on an actual first-strong flip (fixes the
  cursor-drag-cancel bug).
- getNotificationText() wraps embedded message text in a Unicode First-Strong
  Isolate (U+2068..U+2069) so quoted RTL renders correctly inside LTR.
- Grapheme-cluster-safe editing (lib/helpers/ui/grapheme_text_helpers.dart):
  emoji-picker insert and the controller value-setter snap to cluster
  boundaries and repair IME-split surrogate pairs (the "??" corruption); a
  repaired edit also clears the now-stale composing region (the cursor-gap bug).
- Re-enables flutter_test; adds test/rtl_detection_test.dart and
  test/grapheme_text_helpers_test.dart (detection, boundary snapping,
  insert/replace fuzz, IME-split recovery, composing-clear).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01YPSpEnnJze96m53nX9k142

Author: kfatehi

lib/app/components/custom_text_editing_controllers.dart

@@ -96,6 +96,18 @@ class SpellCheckTextEditingController extends TextEditingController {
       return;
     }
 
+    // Repair an edit that split a grapheme cluster (e.g. the IME inserted between
+    // an emoji's surrogate halves while typing in bidi text, which renders "?"),
+    // before any further processing. A repair also clears the now-stale IME
+    // composing region (otherwise a phantom gap appears between caret and text).
+    final repairedValue = repairGraphemeSplitValue(text, newValue);
+    final bool didRepair = repairedValue != null;
+    if (didRepair) {
+      newValue = repairedValue;
+      newText = newValue.text;
+      newOffset = newValue.selection.start;
+    }
+
     if (SettingsSvc.settings.replaceEmoticonsWithEmoji.value) {
       List<(int, int)> offsetsAndDifferences;
       (newText, offsetsAndDifferences) = replaceEmoticons(newText);
@@ -128,6 +140,9 @@ class SpellCheckTextEditingController extends TextEditingController {
       newValue = newValue.copyWith(
         text: newText,
         selection: TextSelection.collapsed(offset: newOffset),
+        // A repaired edit invalidates the IME's composing region (it points into
+        // the pre-repair coordinates), so clear it.
+        composing: didRepair ? TextRange.empty : newValue.composing,
       );
     }
 

lib/app/layouts/conversation_list/widgets/tile/conversation_tile.dart

@@ -191,6 +191,7 @@ class _ChatTitleState extends CustomState<ChatTitle, void, ConversationTileContr
       final _title = controller.chatState.title.value ?? controller.chat.getTitle();
 
       return RichText(
+        textDirection: getTextDirection(_title),
         text: TextSpan(
           children: MessageHelper.buildEmojiText(
             _title,
@@ -274,6 +275,7 @@ class _ChatSubtitleState extends CustomState<ChatSubtitle, void, ConversationTil
       }
 
       final richText = RichText(
+        textDirection: getTextDirection(_subtitle),
         text: subtitleSpan,
         overflow: TextOverflow.ellipsis,
         maxLines: maxLines,

lib/app/layouts/conversation_view/widgets/message/reply/reply_bubble.dart

@@ -98,6 +98,7 @@ class _ReplyBubbleState extends State<ReplyBubble> with ThemeHelpers {
                 style: context.textTheme.labelLarge!.copyWith(color: context.theme.colorScheme.onSurface),
                 maxLines: 2,
                 overflow: TextOverflow.ellipsis,
+                textDirection: getTextDirection(text),
               ),
             ),
           ),
@@ -224,6 +225,7 @@ class _ReplyBubbleState extends State<ReplyBubble> with ThemeHelpers {
                                                 builder: (context, snapshot) {
                                                   if (snapshot.data != null) {
                                                     return RichText(
+                                                      textDirection: getTextDirection(part.fullText),
                                                       text: TextSpan(
                                                         children: snapshot.data!,
                                                       ),

lib/app/layouts/conversation_view/widgets/message/send_animation.dart

@@ -336,6 +336,7 @@ class _SendAnimationState extends CustomState<SendAnimation, SendData, Conversat
                               ? const EdgeInsets.only(left: 3, right: 3)
                               : EdgeInsets.zero,
                           child: RichText(
+                            textDirection: getTextDirection(message!.fullText),
                             text: TextSpan(
                               children: buildMessageSpans(context,
                                   MessagePart(part: 0, text: message!.text, subject: message!.subject), message!,

lib/app/layouts/conversation_view/widgets/message/text/text_bubble.dart

@@ -182,6 +182,7 @@ class _TextBubbleState extends State<TextBubble> with ThemeHelpers {
                           return Transform.scale(scale: value1, alignment: Alignment.center, child: child);
                         },
                         child: RichText(
+                          textDirection: getTextDirection(part.fullText),
                           text: TextSpan(
                             children: snapshot.data!,
                           ),
@@ -194,6 +195,7 @@ class _TextBubbleState extends State<TextBubble> with ThemeHelpers {
                       padding:
                           message.fullText.length == 1 ? const EdgeInsets.only(left: 3, right: 3) : EdgeInsets.zero,
                       child: RichText(
+                        textDirection: getTextDirection(part.fullText),
                         text: TextSpan(
                           children: snapshot.data!,
                         ),

lib/app/layouts/conversation_view/widgets/text_field/conversation_text_field.dart

@@ -99,8 +99,11 @@ class ConversationTextFieldState extends CustomState<ConversationTextField, void
         String text = realController.text;
         TextSelection selection = realController.selection;
 
-        realController.text = text.substring(0, selection.start) + emoji + text.substring(selection.end);
-        realController.selection = TextSelection.collapsed(offset: selection.start + emoji.length);
+        // Grapheme-safe: snap to cluster boundaries so inserting an emoji next to
+        // another emoji / ZWJ sequence never splits a surrogate pair (renders "?").
+        final r = graphemeSafeReplace(text, selection.start, selection.end, emoji);
+        realController.text = r.text;
+        realController.selection = TextSelection.collapsed(offset: r.caret);
 
         (controller.editing.lastOrNull?.controller.focusNode ?? controller.lastFocusedNode).requestFocus();
       });