refactor(build): move side-effect config to vite.config, clean up package.json

Replace src/ patterns in package.json#sideEffects with
treeshake.moduleSideEffects: true in rolldownOptions. The sideEffects
field is a public contract for consumer bundlers — it should only
describe published dist/ files, not src/ files that are never shipped.
Build-time side-effect behaviour belongs in the build config.

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

Author: iOvergaard

package.json

@@ -20,10 +20,7 @@
   "sideEffects": [
     "!dist/components/**/*.element.js",
     "!dist/internal/index.js",
-    "!src/components/**/*.element.ts",
-    "!src/internal/index.ts",
-    "dist/**/*.js",
-    "src/**/*.ts"
+    "dist/**/*.js"
   ],
   "customElements": "custom-elements.json",
   "files": [

vite.config.ts

@@ -38,6 +38,7 @@ export default defineConfig({
     },
     rolldownOptions: {
       external: [/^lit/, /^culori/],
+      treeshake: { moduleSideEffects: true },
       output: {
         preserveModules: true,
         preserveModulesRoot: 'src',