feat: new leaf-pair favicon, shown in the About dialog

Two asymmetric blades on a ground line, in the slate/clay brand
colors, replace the old page-lines icon. The old favicon is kept as
favicon-old.svg. The About dialog shows it above the wordmark.

public/favicon-old.svg

@@ -0,0 +1,4 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 32 32">
+  <rect width="24" height="30" x="4" y="1" rx="2" fill="#fff" stroke="#334155" stroke-width="1.5"/>
+  <path d="M8 8h16M8 13h16M8 18h12M8 23h14" stroke="#3b82f6" stroke-width="1.5" stroke-linecap="round"/>
+</svg>

public/favicon.svg

@@ -1,4 +1,5 @@
 <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 32 32">
-  <rect width="24" height="30" x="4" y="1" rx="2" fill="#fff" stroke="#334155" stroke-width="1.5"/>
-  <path d="M8 8h16M8 13h16M8 18h12M8 23h14" stroke="#3b82f6" stroke-width="1.5" stroke-linecap="round"/>
+  <line x1="6" y1="31" x2="26" y2="31" stroke="#202b36" stroke-width="1.25" opacity="0.3"/>
+  <path transform="translate(11,31)" d="M0,0 C-3.895,-9.912 -2.832,-19.824 0,-25.488 C2.832,-19.824 3.895,-9.912 0,0 Z" fill="#4c6c8a"/>
+  <path transform="translate(21,31)" d="M0,0 C-4.583,-11.667 -3.333,-23.333 0,-29.167 C3.333,-23.333 4.583,-11.667 0,0 Z" fill="#d1734f"/>
 </svg>

src/lib/components/AboutDialog.svelte

@@ -41,6 +41,8 @@
       </svg>
     </button>
 
+    <img class="icon" src="/favicon.svg" alt="" aria-hidden="true" />
+
     <img class="logo" src="/EdenText.png" alt="EdenText" />
 
     <p class="tagline">{t().about.tagline}</p>
@@ -128,10 +130,15 @@
     color: var(--color-text);
   }
 
+  .icon {
+    height: 40px;
+    width: auto;
+    margin-top: 4px;
+  }
+
   .logo {
     height: 30px;
     width: auto;
-    margin-top: 4px;
   }
 
   .tagline {