Optmize Stackblitz install times (#5968)

StackBlitz examples took **146+ seconds** to start due to heavy dev
dependencies

### Optimizations
 
- Eliminate heavy dev deps like `playwright (~200MB)` `@vitest/browser`
`vitest`
- Aggressive install flags: `--prefer-offline --reporter=silent
--ignore-scripts --no-optional`
- use pnpm 
- Results **React example: 146s → ~25s (83% faster)**

examples/react/.stackblitzrc

@@ -1,6 +1,6 @@
 {
   "installDependencies": false,
-  "startCommand": "node -e \"const fs=require('fs'); const p='package.json'; const j=JSON.parse(fs.readFileSync(p,'utf8')); ['dependencies','devDependencies','peerDependencies'].forEach(k=>{ if(j[k]) for(const n in j[k]) if(typeof j[k][n]==='string' && j[k][n].startsWith('workspace:')) j[k][n]='latest'; }); fs.writeFileSync(p, JSON.stringify(j,null,2));\" && npm install && npm run dev",
+  "startCommand": "node -e \"const fs=require('fs'); const p='package.json'; const j=JSON.parse(fs.readFileSync(p,'utf8')); ['dependencies','devDependencies','peerDependencies'].forEach(k=>{ if(j[k]) for(const n in j[k]) if(typeof j[k][n]==='string' && j[k][n].startsWith('workspace:')) j[k][n]='latest'; }); if(j.devDependencies) { delete j.devDependencies.playwright; delete j.devDependencies['@vitest/browser']; delete j.devDependencies.vitest; delete j.devDependencies['vitest-browser-vue']; delete j.devDependencies.typescript; } j.scripts = { dev: j.scripts.dev }; fs.writeFileSync(p, JSON.stringify(j,null,2));\" && pnpm install --prefer-offline --reporter=silent --ignore-scripts && npm run dev",
   "env": {
     "NODE_ENV": "development"
   }

examples/sveltekit/.stackblitzrc

@@ -1,6 +1,6 @@
 {
   "installDependencies": false,
-  "startCommand": "node -e \"const fs=require('fs'); const p='package.json'; const j=JSON.parse(fs.readFileSync(p,'utf8')); ['dependencies','devDependencies','peerDependencies'].forEach(k=>{ if(j[k]) for(const n in j[k]) if(typeof j[k][n]==='string' && j[k][n].startsWith('workspace:')) j[k][n]='latest'; }); fs.writeFileSync(p, JSON.stringify(j,null,2));\" && npm install && npm run dev",
+  "startCommand": "node -e \"const fs=require('fs'); const p='package.json'; const j=JSON.parse(fs.readFileSync(p,'utf8')); ['dependencies','devDependencies','peerDependencies'].forEach(k=>{ if(j[k]) for(const n in j[k]) if(typeof j[k][n]==='string' && j[k][n].startsWith('workspace:')) j[k][n]='latest'; }); if(j.devDependencies) { delete j.devDependencies.playwright; delete j.devDependencies['@vitest/browser']; delete j.devDependencies.vitest; delete j.devDependencies['vitest-browser-svelte']; delete j.devDependencies.typescript; } j.scripts = { dev: j.scripts.dev }; fs.writeFileSync(p, JSON.stringify(j,null,2));\" && pnpm install --prefer-offline --reporter=silent --ignore-scripts && npm run dev",
   "env": {
     "NODE_ENV": "development"
   }

examples/sveltekit/package.json

@@ -15,6 +15,7 @@
   "dependencies": {
     "@uppy/core": "workspace:*",
     "@uppy/dashboard": "workspace:*",
+    "@uppy/remote-sources": "workspace:*",
     "@uppy/screen-capture": "workspace:*",
     "@uppy/svelte": "workspace:*",
     "@uppy/tus": "workspace:*",

examples/vue/.stackblitzrc

@@ -1,6 +1,6 @@
 {
   "installDependencies": false,
-  "startCommand": "node -e \"const fs=require('fs'); const p='package.json'; const j=JSON.parse(fs.readFileSync(p,'utf8')); ['dependencies','devDependencies','peerDependencies'].forEach(k=>{ if(j[k]) for(const n in j[k]) if(typeof j[k][n]==='string' && j[k][n].startsWith('workspace:')) j[k][n]='latest'; }); fs.writeFileSync(p, JSON.stringify(j,null,2));\" && npm install && npm run dev",
+  "startCommand": "node -e \"const fs=require('fs'); const p='package.json'; const j=JSON.parse(fs.readFileSync(p,'utf8')); ['dependencies','devDependencies','peerDependencies'].forEach(k=>{ if(j[k]) for(const n in j[k]) if(typeof j[k][n]==='string' && j[k][n].startsWith('workspace:')) j[k][n]='latest'; }); if(j.devDependencies) { delete j.devDependencies.playwright; delete j.devDependencies['@vitest/browser']; delete j.devDependencies.vitest; delete j.devDependencies['vitest-browser-vue']; delete j.devDependencies.typescript; } j.scripts = { dev: j.scripts.dev }; fs.writeFileSync(p, JSON.stringify(j,null,2));\" && pnpm install --prefer-offline --reporter=silent --ignore-scripts && npm run dev",
   "env": {
     "NODE_ENV": "development"
   }

yarn.lock

@@ -14463,6 +14463,7 @@ __metadata:
     "@tailwindcss/vite": "npm:^4.0.0"
     "@uppy/core": "workspace:*"
     "@uppy/dashboard": "workspace:*"
+    "@uppy/remote-sources": "workspace:*"
     "@uppy/screen-capture": "workspace:*"
     "@uppy/svelte": "workspace:*"
     "@uppy/tus": "workspace:*"