feat(markdown): add theme-aware styling for code blocks

Set code block background color and font based on the current IDE theme. This ensures consistent appearance with the editor's theme.

Author: phodal

core/src/main/kotlin/cc/unitmesh/devti/sketch/ui/code/MarkdownViewer.kt

@@ -1,8 +1,12 @@
 package cc.unitmesh.devti.sketch.ui.code
 
+import com.intellij.openapi.editor.colors.EditorColorsManager
 import com.intellij.openapi.util.text.StringUtil
 import com.intellij.temporary.gui.block.LineSpacingExtension
+import com.intellij.ui.BrowserHyperlinkListener
+import com.intellij.ui.ColorUtil
 import com.intellij.util.ui.HTMLEditorKitBuilder
+import com.intellij.util.ui.UIUtil
 import javax.swing.JEditorPane
 import javax.swing.text.DefaultCaret
 
@@ -15,6 +19,14 @@ object MarkdownViewer {
                 LineSpacingExtension(0.2f)
             ).build()
 
+        val backgroundColor = UIUtil.getPanelBackground()
+        val schemeForCurrentUITheme = EditorColorsManager.getInstance().schemeForCurrentUITheme
+        val editorFontName = schemeForCurrentUITheme.editorFontName
+        val editorFontSize = schemeForCurrentUITheme.editorFontSize
+        val fontFamilyAndSize =
+            "font-family:'" + editorFontName + "'; font-size:" + editorFontSize + "pt;"
+        val backgroundColorCss = "background-color: #" + ColorUtil.toHex(backgroundColor) + ";"
+        htmlEditorKit.getStyleSheet().addRule("code { $backgroundColorCss$fontFamilyAndSize}")
         htmlEditorKit.getStyleSheet().addRule("p {margin-top: 1px}")
 
         jEditorPane.also {
@@ -35,6 +47,7 @@ object MarkdownViewer {
             (jEditorPane.caret as? DefaultCaret)?.updatePolicy = 1
         }
 
+        jEditorPane.addHyperlinkListener(BrowserHyperlinkListener.INSTANCE);
         return jEditorPane
     }