feat: Implement Gogh Theme Engine with options page, theme parsing, and semantic theme derivation

We're cooked. <skull emoji>

- Added options page for YAML palette editing, live color preview, and diagnostics.
- Implemented theme engine to parse Gogh YAML palettes and derive semantic themes.
- Configured TypeScript and Vite for building the extension.
- Created new tab and popup HTML pages with corresponding scripts and styles.
- Established storage management for user configurations in Chrome storage.
- Added icons for the extension and updated manifest for MV3 compatibility.

gogh-theme-engine/public/icons/icon.svg

@@ -0,0 +1,6 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 128 128">
+  <rect width="128" height="128" rx="20" fill="#282a36"/>
+  <text x="64" y="80" font-family="Arial, sans-serif" font-size="64" text-anchor="middle" fill="#f8f8f2">G</text>
+  <circle cx="96" cy="32" r="12" fill="#ff79c6"/>
+  <circle cx="96" cy="32" r="6" fill="#bd93f9"/>
+</svg>