Add proj4 as external dependency in Vite config (#3)

* Add proj4 as external dependency in Vite config

Updated the Vite configuration to treat 'proj4' as an external dependency alongside 'maplibre-gl', and added its global mapping for UMD builds. This prevents bundling 'proj4' into the library output.

* Create chilly-jeans-knock.md

Author: huanglii

.changeset/chilly-jeans-knock.md

@@ -0,0 +1,5 @@
+---
+'@naivemap/maplibre-gl-image-layer': patch
+---
+
+Add proj4 as external dependency in Vite config

packages/maplibre-gl-image-layer/vite.config.ts

@@ -10,16 +10,15 @@ export default defineConfig({
   build: {
     lib: {
       entry: resolve(__dirname, 'src/index.ts'),
-      name: 'ImageLayer', // 暴露的全局变量名
-      fileName: 'index' // 输出的包文件名
+      name: 'ImageLayer',
+      fileName: 'index'
     },
     rollupOptions: {
-      // 确保外部化处理那些你不想打包进库的依赖
-      external: ['maplibre-gl'],
+      external: ['maplibre-gl', 'proj4'],
       output: {
-        // 在 UMD 构建模式下为这些外部化的依赖提供一个全局变量
         globals: {
-          'maplibre-gl': 'maplibregl'
+          'maplibre-gl': 'maplibregl',
+          proj4: 'proj4'
         }
       }
     }