fix(dsl): render tabs as a fixed-width gap

A literal tab advanced text to the next platform tab stop, which pushed
the rest of the line far enough to wrap it mid-phrase.

Replace each tab with an en space so the separator keeps a fixed, modest
width and the line breaks like ordinary text.

app/src/main/java/com/example/research/ui/article/DslAnnotatedParser.kt

@@ -136,6 +136,15 @@ object DslAnnotatedParser {
             }
         }
 
+        fun appendText(value: String) {
+            if (value.isEmpty()) return
+            builder.append(value)
+            if (refStack.isNotEmpty()) {
+                refStack.last().second.append(value)
+            }
+            lastAppended = value.last()
+        }
+
         fun marginIndent(tagName: String): Int {
             if (tagName == "m" || tagName == "m0" || tagName == "m1") return 0
             val margin = tagName.drop(1).toIntOrNull() ?: return 0
@@ -253,6 +262,10 @@ object DslAnnotatedParser {
                     }
                     i++
                 }
+                '\t' -> {
+                    appendText("\u2002")
+                    i++
+                }
                 else -> {
                     appendChar(char)