fix(android): correct insertion boundary in FormattingStore and add serializer bounds check

Change adjustForEdit to shift ranges when editLocation == range.start
(using >= instead of >), matching iOS behavior. Without this, typing
at the start of a formatted range fails to shift it, causing the
inserted character to incorrectly inherit the style.

Add bounds clamping in MarkdownSerializer to prevent
StringIndexOutOfBoundsException if the formatting store ever contains
ranges that exceed the text length.

Made-with: Cursor

Author: hryhoriiK97

android/src/main/java/com/swmansion/enriched/markdown/input/formatting/FormattingStore.kt

@@ -140,7 +140,7 @@ class FormattingStore {
         }
       } else {
         when {
-          range.start > editLocation -> {
+          range.start >= editLocation -> {
             range.start += insertedLength
             range.end += insertedLength
           }

android/src/main/java/com/swmansion/enriched/markdown/input/formatting/MarkdownSerializer.kt

@@ -12,8 +12,10 @@ object MarkdownSerializer {
 
     val events = ArrayList<BoundaryEvent>(ranges.size * 2)
     for (range in ranges) {
-      var start = range.start
-      var end = range.end
+      var start = range.start.coerceIn(0, text.length)
+      var end = range.end.coerceIn(0, text.length)
+
+      if (start >= end) continue
 
       // Trim leading/trailing whitespace so delimiters hug non-whitespace content
       while (start < end && text[start].isWhitespace()) start++