[Work Item] Implement get_sampling_features() method

[Sam-Bolling]

📌 Task Description

Implement the getSamplingFeatures(params: Record<string, string>) method in src/client/connectedSystemsClient.ts. This method should retrieve sampling feature metadata from CSAPI-compliant servers using flexible query parameters.

This method is part of the extended CSAPI support and should follow the same modular, compositional design as core methods. It will be exposed via .connectedSystems only if CSAPI capability is detected.

✅ Acceptance Criteria

• Method getSamplingFeatures(params: Record<string, string>) created
• Returns parsed response from CSAPI /sampling-features endpoint
• Integrated into ConnectedSystemsClient class
• Covered by unit tests using vitest or jest
• Includes JSDoc comments for documentation
• Linked to GitHub Project board

🔗 Related Links

• Implementation Plan
• Upstream Issue #118