feat(repo-tabs): add context menu for managing repository tabs

This update introduces a context menu for repository tabs, allowing users
to easily close individual tabs, close all other tabs, or close tabs to the
right. Additionally, several visual elements related to loading animations
have been removed to streamline the user interface.

- Implement context menu actions for repository tab management
- Remove unnecessary loading animations from the splash screen and overlays
- Enhance user experience with improved tab management functionality

public/splashscreen.html

@@ -66,15 +66,6 @@
         overflow: hidden;
       }
 
-      .splash::before {
-        content: "";
-        position: absolute;
-        inset: 0;
-        background: linear-gradient(110deg, transparent 0%, rgba(160, 124, 255, 0.12) 48%, transparent 54%);
-        transform: translateX(-100%);
-        animation: card-scan 2.8s ease-in-out infinite;
-      }
-
       .mark {
         position: relative;
         display: grid;
@@ -145,18 +136,6 @@
         animation: icon-float 2.4s ease-in-out infinite;
       }
 
-      .sheen {
-        position: absolute;
-        z-index: 2;
-        width: 112px;
-        height: 172px;
-        border-radius: 50%;
-        background: linear-gradient(90deg, transparent 8%, rgba(255, 255, 255, 0.18), transparent 72%);
-        mix-blend-mode: screen;
-        transform: translateX(-98px) rotate(16deg);
-        animation: icon-sheen 2.8s ease-in-out infinite;
-      }
-
       .copy {
         position: relative;
         display: grid;
@@ -202,22 +181,11 @@
         to { transform: translate3d(42px, 42px, 0); }
       }
 
-      @keyframes card-scan {
-        0%, 34% { transform: translateX(-100%); }
-        72%, 100% { transform: translateX(100%); }
-      }
-
       @keyframes icon-float {
         0%, 100% { transform: translateY(0) scale(1); }
         50% { transform: translateY(-5px) scale(1.015); }
       }
 
-      @keyframes icon-sheen {
-        0%, 18% { transform: translateX(-98px) rotate(16deg); opacity: 0; }
-        44% { opacity: 0.9; }
-        68%, 100% { transform: translateX(98px) rotate(16deg); opacity: 0; }
-      }
-
       @keyframes halo-breathe {
         0%, 100% { opacity: 0.35; transform: rotate(45deg) scale(0.95); }
         50% { opacity: 0.8; transform: rotate(45deg) scale(1.04); }
@@ -236,11 +204,9 @@
 
       @media (prefers-reduced-motion: reduce) {
         .grid,
-        .splash::before,
         .halo,
         .trace,
         .icon,
-        .sheen,
         .bar span {
           animation: none;
         }
@@ -264,7 +230,6 @@
           <path class="trace base" d="M46 180 L174 180" />
         </svg>
         <img class="icon" src="/splash-icon.png" alt="" />
-        <span class="sheen"></span>
       </div>
       <div class="copy">
         <strong>GitLite</strong>