perf(build): emit ESM per source module so consumers can tree-shake

CLAUDE.md

@@ -422,7 +422,8 @@ See `examples/vite/src/index.scss` for the reference layer setup.
 - `stream-chat-react/emojis` — Emoji picker plugin (`src/plugins/Emojis/`)
 - `stream-chat-react/mp3-encoder` — MP3 encoding for voice messages (`src/plugins/encoders/mp3.ts`)
 
-Vite config: no minification, sourcemaps enabled, all deps externalized. Target: ES2020.
+Vite config: no minification, sourcemaps enabled, all deps externalized. Target: ES2022
+(inherited from `tsconfig.lib.json`'s `compilerOptions.target`, so the two never drift).
 
 ### i18n System
 

package.json

@@ -259,11 +259,6 @@
       "built": true
     }
   },
-  "browserslist": [
-    ">0.2%",
-    "not ie <= 11",
-    "not op_mini all"
-  ],
   "packageManager": "yarn@4.15.0",
   "workspaces": [
     "examples/*"

vite.config.ts

@@ -26,6 +26,7 @@ export default defineConfig({
         'slot-layout': resolve(__dirname, './src/plugins/SlotLayout/index.tsx'),
       },
     },
+    // `yarn build` already wipes dist up front via `yarn clean`
     emptyOutDir: false,
     outDir: 'dist',
     minify: false,
@@ -45,6 +46,11 @@ export default defineConfig({
           chunkFileNames: `${dir}/[name].[hash].${extension}`,
           entryFileNames: `${dir}/[name].${extension}`,
           hashCharacters: 'hex',
+          // Emit the ESM build as one file per source module. Consumer bundlers
+          // drop whole modules (guided by our package.json `sideEffects`) before
+          // they attempt statement-level elimination. The CJS build stays chunked,
+          // as CJS is not tree-shaken by consumers either way.
+          preserveModules: format === 'es',
         };
       }),
     },