Issue: Invoke-WebRequest and wget were downloading HTML login page
instead of raw file content due to GitLab authentication requirement.

**Changes:**

Windows Guide:
- Added Option A: Download via web browser (recommended)
- Added Option B: Use git clone (works with auth)
- Added Option C: Copy from WSL2
- Added file verification command to detect HTML vs YAML
- Updated WSL2 Ubuntu section with git clone method

Linux README:
- Replaced wget with git clone in Quick Start
- Replaced wget with git clone in Download Compose File section
- Added verification step (head -n 5 to check for HTML)

**Why this fix:**
- GitLab raw file URLs require authentication
- wget/Invoke-WebRequest download sign-in page HTML
- git clone properly handles GitLab authentication
- Users get valid YAML file, not HTML

All download methods now work correctly with authenticated repository.