Add UnicodeTrayDemo to demonstrate cross-locale Unicode support in tray menus

- Introduced `UnicodeTrayDemo` showcasing a tray menu with French, Chinese, and mixed Unicode items.
- Validates UTF-8 to UTF-16 handling and rendering across platforms.
- Includes examples of accented letters, non-Latin scripts, and symbols in a multi-language context.

Author: kdroidFilter

demo/src/jvmMain/kotlin/com/kdroid/composetray/demo/UnicodeTrayDemo.kt

@@ -0,0 +1,106 @@
+package com.kdroid.composetray.demo
+
+import androidx.compose.foundation.Image
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.window.Window
+import androidx.compose.ui.window.application
+import com.kdroid.composetray.tray.api.Tray
+import composenativetray.demo.generated.resources.Res
+import composenativetray.demo.generated.resources.icon
+import org.jetbrains.compose.resources.painterResource
+
+/**
+ * UnicodeTrayDemo
+ *
+ * Demonstrates a tray menu with French and Chinese items, including special
+ * characters like accented letters (é, à, ç) and punctuation.
+ * This validates end-to-end UTF-8 → UTF-16 handling on Windows and generic
+ * Unicode rendering across platforms.
+ */
+fun main() = application {
+    val painter = painterResource(Res.drawable.icon)
+
+    var lastClicked by remember { mutableStateOf("-") }
+
+    Tray(
+        iconContent = {
+            Image(painter = painter, contentDescription = "Unicode Tray", modifier = Modifier.fillMaxSize())
+        },
+        primaryAction = {
+            // no-op: right-click to open menu
+        },
+        tooltip = "Démo: Menu Unicode (Français/中文)"
+    ) {
+        // French items
+        Item(label = "Bonjour – Édition") {
+            lastClicked = "Bonjour – Édition"
+            println("Clicked: $lastClicked")
+        }
+        Item(label = "Préférences…") {
+            lastClicked = "Préférences…"
+            println("Clicked: $lastClicked")
+        }
+        Item(label = "À propos") {
+            lastClicked = "À propos"
+            println("Clicked: $lastClicked")
+        }
+        Item(label = "Quitter") {
+            lastClicked = "Quitter"
+            println("Clicked: $lastClicked")
+            exitApplication()
+        }
+
+        Divider()
+
+        // Chinese submenu with mixed content
+        SubMenu(label = "设置 / 設置") {
+            Item(label = "语言：中文（简体）") {
+                lastClicked = "语言：中文（简体）"
+                println("Clicked: $lastClicked")
+            }
+            Item(label = "語言：中文（繁體）") {
+                lastClicked = "語言：中文（繁體）"
+                println("Clicked: $lastClicked")
+            }
+            CheckableItem(label = "启用高级选项 ✓", checked = true) { checked ->
+                lastClicked = "启用高级选项: ${if (checked) "开" else "关"}"
+                println("Clicked: $lastClicked")
+            }
+        }
+
+        SubMenu(label = "信息 ℹ / 信息") {
+            Item(label = "关于 / 關於") {
+                lastClicked = "关于 / 關於"
+                println("Clicked: $lastClicked")
+            }
+            Item(label = "退出 / 退出") {
+                lastClicked = "退出"
+                println("Clicked: $lastClicked")
+                exitApplication()
+            }
+        }
+
+        Divider()
+
+        // Mixed accents and symbols
+        Item(label = "Café crème – façade – piñata – coöperate") {
+            lastClicked = "Café crème – façade – piñata – coöperate"
+            println("Clicked: $lastClicked")
+        }
+        Item(label = "Symbols: € £ ¥ • — … ✓ ✗ © ® ™") {
+            lastClicked = "Symbols"
+            println("Clicked: $lastClicked")
+        }
+
+        Divider()
+
+        Item(label = "Dernier: $lastClicked", isEnabled = false)
+    }
+
+    Window(onCloseRequest = ::exitApplication, title = "Unicode Tray Demo") { }
+}