Remove private Reflection.Emit inspection

[nickna]

Summary

• remove the disabled-by-default ILLabelValidator that reflected over private PersistedAssemblyBuilder label, branch, type, method, and constructor state
• remove the generator yield-star reader of private IL bytes and stack-depth fields; state-machine multi-operand emission already uses SpillBoxed locals before suspension
• lower the AOT analyzer ratchet from 116 to 102 warnings and update the Native AOT plan

Trade-off

GenerateMetadata remains the mandatory validator for unmarked branch targets, but failures no longer receive the optional SHARPTS_VALIDATE_LABELS pre-pass's method-specific context. Preserving that duplicate diagnostic faithfully would require routing 2,126 GetILGenerator acquisitions across 250 files through a wrapper.

Verification

• dotnet test SharpTS.Tests/SharpTS.Tests.csproj --no-restore: 16,266 passed
• focused generator/yield-star/IL verification suites: 653 passed
• AOT analyzer: 102 warnings (IL2075 36 -> 22; all other categories unchanged)
• win-arm64 Native AOT publish and Examples/AotCompileGate/main.ts smoke: 42
• native image: 93,400,064 bytes (98,816 bytes smaller than the prior checkpoint)