Reduce metadata contention while preserving runspace safety

[Copilot]

Runspace serialization stabilized analysis but regressed performance against upstream. These changes reduce work entering the locks without relaxing synchronization; end-to-end gains remain unmeasured.

• Metadata and caching

  • Skip unused casing/export metadata requests and eliminate cache-hit allocations.
  • Cache immutable snapshots and mandatory-parameter summaries for static cmdlets; retain locked, uncached queries for dynamic metadata.
  • Share manifest results and errors within one analysis, preserving freshness between analyses.

• Safety invariants

  • Preserve reentrant locking, lookup-before-lock ordering, cache bypass, fault eviction, and qualified Get-Command retries.

• Performance comparison

  • Compare pinned upstream main, fork main, and fork perf across repeated fresh-process cold/warm runs.
  • Report medians/ranges, verify full diagnostic fingerprints, and optionally collect lock-wait/hold times and cache counters.
  • Retry failed upstream attempts until success or job timeout; retain failure logs and mark affected comparisons ⚠️, explicitly identifying successful-attempt timing bias.