feat: add element-inspector

- Implemented Rulers component for zoom/pan-aware rulers on canvas.
- Created Stage component to serve as a zoomable and pannable viewport for the device frame.
- Developed Toolbar component for responsive controls, including device presets and zoom functionalities.
- Introduced useFrame composable to manage iframe interactions and inspections.
- Established a reactive store to manage application state, including guides and viewport dimensions.
- Added utility functions for color parsing and box model calculations.
- Integrated Tailwind CSS for styling and improved scrollbar aesthetics.
- Implemented unit tests for color utilities and rectangle calculations.
- Configured TypeScript and Vite for the project setup.

element-inspector/vite.config.ts

@@ -0,0 +1,22 @@
+import { defineConfig } from 'vite';
+import VueJsxVapor from 'vue-jsx-vapor/vite';
+import tailwindcss from '@tailwindcss/vite';
+import webExtension from 'vite-plugin-web-extension';
+
+// Element Inspector — Chrome MV3 extension.
+// JSX is compiled to Vue Vapor (no interop); Tailwind v4 compiles the overlay styles,
+// which are injected into a Shadow DOM at runtime. `webExtension` wires the manifest
+// entrypoints (background + content script) into the build.
+export default defineConfig({
+  plugins: [
+    VueJsxVapor(),
+    tailwindcss(),
+    webExtension({
+      manifest: 'manifest.json',
+      browser: 'chrome',
+      // Just build/watch into dist/ — we load it unpacked ourselves rather than
+      // auto-launching a browser via web-ext.
+      disableAutoLaunch: true,
+    }),
+  ],
+});