Update Search-Spotify limit constraints (max 50→10)

## Context

Part of the Spotify Feb 2026 API changes (#70).

- Search `limit` maximum reduced from 50 → 10
- Search `limit` default changed from 20 → 5

## Action
- Review `Search-Spotify` cmdlet for hardcoded or validated limit values
- Update any `ValidateRange` or default parameter values accordingly
- Pagination logic may need adjustment since fewer results come back per page