feat: add hello world 3 file and PRP documentation

[Wirasm]

Summary

This PR creates a simple text file named hello-world-3.txt in the root directory with the content "Hello from parallel work order 3!". This demonstrates basic file creation and content writing functionality as part of parallel work order 3 testing.

Changes

• Created PRP documentation at PRPs/features/completed/create-hello-world-3-file.md
• Created hello-world-3.txt with greeting message

Implementation Details

This implementation follows the KISS (Keep It Simple, Stupid) and YAGNI (You Aren't Gonna Need It) principles outlined in CLAUDE.md. The feature requires no dependencies, no complex logic, and implements only what is explicitly needed - a single file with static content.

See: PRPs/features/completed/create-hello-world-3-file.md

Key details:

• Static text file with 37 characters
• No code changes required
• No external dependencies
• Plain text format with UTF-8 encoding

Testing

• File exists in root directory
• File contains correct content: "Hello from parallel work order 3!"
• File has standard read/write permissions
• Git recognizes the file
• No existing files were modified

Related Issues

Part of parallel work order 3 testing.