docs: clarify Docker installation requirements and add platform-specific instructions

- Replace "Docker Desktop" prerequisite with generic "Docker installed"
- Add detailed Docker installation instructions for macOS, Linux, and Windows
- Include package manager options (Homebrew, apt-get, winget, Chocolatey)
- Add Docker verification command
- Update related documentation files for consistency
- Use collapsible section to keep Quick Start clean

Now users understand they can use any Docker installation method, not just Docker Desktop.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

docs/INSTALLATION.md

@@ -27,8 +27,8 @@ docker compose up -d
 
 ### Prerequisites
 
-- Docker Desktop or Docker Engine
-- Docker Compose (included with Docker Desktop)
+- Docker Engine (install via package manager or Docker Desktop)
+- Docker Compose V2 (included with modern Docker installations)
 
 ### Method 1: Using Pre-built Images