feat(ui): replace emoji logos with new app icon across dashboard

- NavMenu: swap 🐢 emoji for <img src="logo.png">
- Login page: swap 🎲 emoji for <img src="logo.png">
- Mini App page: swap 🎲 emoji for <img src="logo.png">
- Replace favicon.png with the new logo
- Add logo.png to wwwroot
- Update CSS for .nav-brand-icon, .login-logo, .mini-app-logo to use object-fit: contain sizing

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/GmRelay.Web/Components/Layout/NavMenu.razor

@@ -2,7 +2,7 @@
 
 <div class="nav-header">
     <a class="nav-brand" href="">
-        <span class="nav-brand-icon">🐢</span>
+        <img src="logo.png" alt="GM-Relay" class="nav-brand-icon" />
         <span class="nav-brand-text">GM-Relay</span>
     </a>
     <button class="nav-toggle" @onclick="ToggleMenu" aria-label="Переключить меню">

src/GmRelay.Web/Components/Layout/NavMenu.razor.css

@@ -16,10 +16,10 @@
 }
 
 .nav-brand-icon {
-    font-size: 1.5rem;
-    line-height: 1;
-    vertical-align: middle;
-    margin-top: -2px;
+    width: 1.5rem;
+    height: 1.5rem;
+    object-fit: contain;
+    display: block;
 }
 
 .nav-brand-text {

src/GmRelay.Web/Components/Pages/Login.razor

@@ -8,7 +8,7 @@
 
 <div class="login-page">
     <div class="login-card">
-        <div class="login-logo">🎲</div>
+        <img src="logo.png" alt="GM-Relay" class="login-logo" />
         <h1 class="login-title">GM-Relay</h1>
         <p class="login-subtitle">Войдите через Telegram для управления игровыми сессиями</p>
 

src/GmRelay.Web/Components/Pages/MiniApp.razor

@@ -8,7 +8,7 @@
 
 <div class="mini-app-page">
     <div class="mini-app-auth-card" data-auth-status="@miniAppAuthStatus">
-        <div class="mini-app-logo">🎲</div>
+        <img src="logo.png" alt="GM-Relay" class="mini-app-logo" />
         <h1>GM-Relay</h1>
         <p>@statusMessage</p>
 

src/GmRelay.Web/wwwroot/app.css

@@ -877,8 +877,13 @@ select option {
 }
 
 .login-logo {
-    font-size: 2.5rem;
+    width: 2.5rem;
+    height: 2.5rem;
+    object-fit: contain;
     margin-bottom: 0.5rem;
+    display: block;
+    margin-left: auto;
+    margin-right: auto;
 }
 
 .login-title {
@@ -919,8 +924,13 @@ select option {
 }
 
 .mini-app-logo {
-    font-size: 2.25rem;
+    width: 2.25rem;
+    height: 2.25rem;
+    object-fit: contain;
     margin-bottom: 0.75rem;
+    display: block;
+    margin-left: auto;
+    margin-right: auto;
 }
 
 .mini-app-auth-card h1 {