Clean up frontend branding and metadata

Replace Vite defaults with Nuzlocke Tracker branding: custom pokeball-
skull favicon (SVG + PNG + ICO), page title, meta description, Open
Graph tags, theme-color, web manifest, and package.json name.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/public/favicon.svg

@@ -0,0 +1,27 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 64 64">
+  <!-- Pokeball top (red) -->
+  <path d="M32 4C16.536 4 4 16.536 4 32h56C60 16.536 47.464 4 32 4z" fill="#DC2626"/>
+  <!-- Pokeball bottom (white) -->
+  <path d="M4 32c0 15.464 12.536 28 28 28s28-12.536 28-28H4z" fill="#F5F5F5"/>
+  <!-- Center band -->
+  <rect x="4" y="29" width="56" height="6" fill="#1F2937"/>
+  <!-- Center circle (dark background for skull) -->
+  <circle cx="32" cy="32" r="12" fill="#1F2937"/>
+  <!-- Skull -->
+  <g transform="translate(32, 30)">
+    <!-- Skull cranium -->
+    <ellipse cx="0" cy="0" rx="8" ry="7.5" fill="#F5F5F5"/>
+    <!-- Left eye -->
+    <ellipse cx="-3" cy="-1" rx="2.2" ry="2.5" fill="#1F2937"/>
+    <!-- Right eye -->
+    <ellipse cx="3" cy="-1" rx="2.2" ry="2.5" fill="#1F2937"/>
+    <!-- Nose -->
+    <path d="M-0.8 3 L0.8 3 L0 4.2z" fill="#1F2937"/>
+    <!-- Teeth -->
+    <rect x="-4.5" y="5.5" width="9" height="3.5" rx="0.8" fill="#F5F5F5" stroke="#1F2937" stroke-width="0.8"/>
+    <line x1="-1.5" y1="5.5" x2="-1.5" y2="9" stroke="#1F2937" stroke-width="0.6"/>
+    <line x1="1.5" y1="5.5" x2="1.5" y2="9" stroke="#1F2937" stroke-width="0.6"/>
+  </g>
+  <!-- Outline -->
+  <circle cx="32" cy="32" r="28" fill="none" stroke="#1F2937" stroke-width="2.5"/>
+</svg>