fix: diagnose conditional semaphore waits

[georgepwall1991]

Summary

• diagnose null-conditional SemaphoreSlim.Wait calls inside async code
• normalize ordinary member access and conditional member binding before existing semantic checks
• preserve conditional zero-timeout exclusions
• intentionally offer no conditional-access fix and update v1.27.196 metadata

Verification

• red: new conditional semaphore wait test expected 1 CC026 diagnostic and received 0
• green: focused CC026 suite passed 11/11
• Release build: 62 expected sample warnings, 0 errors
• full Release suite: 657/657 passed
• packed dependency-free CancelCop.Analyzer.1.27.196.nupkg with both analyzer DLLs
• touched-file whitespace check passed

Review

• self-review requested by repository owner; no Claude review used