feat: add Miku favicon to Web UI with transparent background

.gitignore

@@ -71,6 +71,7 @@ temp_*
 *.jpeg
 *.gif
 !static/images/*
+!bot/static/miku-favicon.png
 
 # Backups
 backups/

bot/static/index.html

@@ -7,6 +7,7 @@
   <meta http-equiv="Pragma" content="no-cache">
   <meta http-equiv="Expires" content="0">
   <title>Miku Control Panel</title>
+  <link rel="icon" href="/static/miku-favicon.png" type="image/png">
   <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/cropperjs/1.6.2/cropper.min.css">
   <script src="https://cdnjs.cloudflare.com/ajax/libs/cropperjs/1.6.2/cropper.min.js"></script>
   <link rel="stylesheet" href="/static/css/style.css?v=20260502">

bot/static/system.html

@@ -4,6 +4,7 @@
     <meta charset="UTF-8">
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <title>🎛️ System Settings - Logging Configuration</title>
+    <link rel="icon" href="/static/miku-favicon.png" type="image/png">
     <style>
         body {
             margin: 0;

bot/static/system_clean.html

@@ -4,6 +4,7 @@
     <meta charset="UTF-8">
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <title>System Settings - Miku Bot</title>
+    <link rel="icon" href="/static/miku-favicon.png" type="image/png">
     <style>
         * {
             margin: 0;