fix: diagnose conditional Task result access

[georgepwall1991]

Summary

• diagnose null-conditional Task<T>/ValueTask<T> .Result access inside async code
• reuse the existing semantic task-like and async-function gates
• intentionally offer no fix because null-preserving await rewrites are context-dependent
• update analyzer health metadata for v1.27.194

Verification

• red: new test expected 1 CC015 diagnostic and received 0
• green: focused CC015 suite passed 19/19
• Release build: 62 expected sample warnings, 0 errors
• full Release suite: 655/655 passed
• packed dependency-free CancelCop.Analyzer.1.27.194.nupkg with both analyzer DLLs
• touched-file whitespace check passed

Review

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