fix(emcn): repair app-wide crash and unstyled UI after package extraction (#5258)

Two regressions from moving emcn into @sim/emcn:

1. optimizePackageImports['@sim/emcn'] rewrote barrel imports to direct subpaths, duplicating the toast module so ToastProvider (layout) and useToast (workspace permissions provider) resolved different ToastContext objects — useToast threw 'must be used within <ToastProvider>' on every workspace route. Removed @sim/emcn from optimizePackageImports.

2. emcn's source left apps/sim's Tailwind content globs (and docs' v4 auto-content scope, which excludes node_modules), so utility classes used only inside emcn components stopped generating and components rendered unstyled. Added the package to apps/sim's Tailwind content and a @source to docs.

apps/docs/app/global.css

@@ -2,6 +2,7 @@
 @import "fumadocs-ui/css/neutral.css";
 @import "fumadocs-ui/css/preset.css";
 @import "fumadocs-openapi/css/preset.css";
+@source "../../../packages/emcn/src";
 
 /* Prevent overscroll bounce effect on the page */
 html,

apps/sim/next.config.ts

@@ -133,7 +133,6 @@ const nextConfig: NextConfig = {
     optimizeCss: true,
     preloadEntriesOnStart: false,
     optimizePackageImports: [
-      '@sim/emcn',
       'lodash',
       'framer-motion',
       'reactflow',

apps/sim/tailwind.config.ts

@@ -6,6 +6,7 @@ export default {
     './pages/**/*.{js,ts,jsx,tsx,mdx}',
     './components/**/*.{js,ts,jsx,tsx,mdx}',
     './app/**/*.{js,ts,jsx,tsx,mdx}',
+    '../../packages/emcn/src/**/*.{js,ts,jsx,tsx}',
     '!./app/node_modules/**',
     '!**/node_modules/**',
   ],