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

[wardbox]

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