fix(ci): remove rm -rf node_modules and ensure dlfetch/src dir exists

The iOS build failed because pre-emb's key replacement step couldn't
find node_modules/@ecool/react-native-dlfetch/src. Two fixes:

1. Remove rm -rf node_modules — rely on CI cache instead of clean
   install, matching the approach used in the last successful iOS build
2. Add mkdir -p as safety net to ensure the target directory exists
   before emb runs its internal npm install + pre-emb key replacement
1 job for main in 1 minute and 24 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
failed #127736
studio-2023 triggered
ci-build

00:01:24

 
Name Stage Failure
failed
ci-build Build
  output: [ null, null, null ],
pid: 82193,
stdout: null,
stderr: null
}

Node.js v18.18.2
Cleaning up project directory and file based variables
ERROR: Job failed: exit status 1