add Markdown surpport

ios/OralTrainer/Views/PlayerSectionView.swift

@@ -256,10 +256,7 @@ struct SentenceExplanationSheet: View {
                             .font(.system(size: 15))
                             .foregroundColor(Theme.textSubtle)
                     } else {
-                        Text(explanation)
-                            .font(.system(size: 16))
-                            .foregroundColor(Theme.textDark)
-                            .lineSpacing(5)
+                        MarkdownExplanationText(text: explanation)
                     }
                 }
                 .frame(maxWidth: .infinity, alignment: .leading)
@@ -320,3 +317,54 @@ struct SentenceExplanationSheet: View {
         )
     }
 }
+
+private struct MarkdownExplanationText: View {
+    let text: String
+
+    var body: some View {
+        Text(Self.attributed(from: text))
+            .font(.system(size: 16))
+            .foregroundColor(Theme.textDark)
+            .tint(Theme.buttonBlue)
+            .lineSpacing(5)
+            .frame(maxWidth: .infinity, alignment: .leading)
+    }
+
+    private static func attributed(from source: String) -> AttributedString {
+        let options = AttributedString.MarkdownParsingOptions(
+            interpretedSyntax: .full,
+            failurePolicy: .returnPartiallyParsedIfPossible
+        )
+        if let parsed = try? AttributedString(
+            markdown: preservingLineBreaks(source),
+            options: options
+        ) {
+            return parsed
+        }
+        return AttributedString(source)
+    }
+
+    private static func preservingLineBreaks(_ source: String) -> String {
+        let normalized = source
+            .replacingOccurrences(of: "\r\n", with: "\n")
+            .replacingOccurrences(of: "\r", with: "\n")
+        var result = ""
+        var inFence = false
+        let lines = normalized.split(separator: "\n", omittingEmptySubsequences: false)
+        for (index, rawLine) in lines.enumerated() {
+            let line = String(rawLine)
+            let trimmed = line.trimmingCharacters(in: .whitespaces)
+            if trimmed.hasPrefix("```") {
+                inFence.toggle()
+            }
+            result += line
+            guard index < lines.count - 1 else { continue }
+            if inFence || trimmed.isEmpty {
+                result += "\n"
+            } else {
+                result += "\n\n"
+            }
+        }
+        return result
+    }
+}