Cache generated PowerShell adapter schemas during discovery #1812

Summary of the new feature / enhancement

Follow-up to #1775: PowerShell adapters generate resource schemas whenever they list cached resource metadata. Generate and persist schemas during cache refresh instead, so repeated discovery does not rebuild them.

Proposed technical implementation details (optional)

Apply to both PowerShell and Windows PowerShell adapters. Store each schema with its resource cache entry, bump cache versions, and preserve invalidation when module files or paths change. Retain per-resource warning/fallback behavior for unexpected metadata. Verify live and cached discovery produce equivalent schemas and measure repeated-listing overhead before and after the change.