[Work Item] Add usage examples to README

[Sam-Bolling]

📌 Task Description

Add usage examples to the project README that demonstrate how to interact with CSAPI methods via the main client. Include examples for core methods such as getSystems(), getObservations(), and getCommands().

Examples should reflect TypeScript syntax and show how .connectedSystems is conditionally exposed based on capability detection. This helps contributors and downstream users understand how to use the client in real-world scenarios.

✅ Acceptance Criteria

• README includes CSAPI usage examples
• Examples use TypeScript syntax
• Demonstrates conditional access to .connectedSystems
• Covers at least 2–3 core methods
• Linked to GitHub Project board

🔗 Related Links

• Implementation Plan
• Upstream Issue #118