Installation instructions in README.md incomplete

[cyrille-artho]

Bug Description:

The installation instructions lack a description of all the TypeScript and JavaScript dependencies that have to be installed. On a clean machine, the build fails, and commonly available information on the WWW only gets one so far in resolving these dependencesi.

Steps to Reproduce:

1. Install nvm v0.40.3.
2. Install npm packages: npm install -g typescript npm install -g concurrently npm install -g lerna npm install -g theia
3. Install yarn packages: yarn global add mocha yarn global add playwright

However, even after these steps, the build fails because "Playwright" cannot be found. Below is the first line from the build log:

playwright-tests/tests/page-objects/theia-trace-viewer-app.ts(30,42): error TS2307: Cannot find module '@theia/playwright' or its corresponding type declarations. 

Additional Information

• Operating System: Ubuntu 22.04.5 LTS (GNU/Linux 5.15.0-156-generic x86_64)
• Theia Version: Latest version from git repo (2025-09-25, hash b01f65b4c28fe5e11834e6d685fb5173cd336fdd)