fix: restore Core project compilation — remove Compile Remove, fix API mismatches (#342)

[JusterZhu]

Summary

Restores compilation for the entire \GeneralUpdate.Core\ project. Previously, all Bootstrap, Strategy, SilentUpdateMode, and Pipeline files were excluded via <Compile Remove>\ directives — only the abstract base layer compiled. Now the full project builds.

Changes

• *Removed <Compile Remove>* for Bootstrap (GeneralUpdateBootstrap, GeneralClientBootstrap, GeneralUpdateOSS, GeneralClientOSS), all Strategies (Windows, Linux, OSS, Mac), SilentUpdateMode, and PatchMiddleware
• PatchMiddleware rewritten as no-op stub — waits for T2 (IBinaryDiffer interface extraction) to resolve circular dependency with GeneralUpdate.Differential
• MacStrategy fixed: .Use(new HashMiddleware())\ → .UseMiddleware()\ (matching PipelineBuilder API)
• BlackListManager API mismatches fixed: \AddBlackFileFormats\ → \AddBlackFormats, \BlackFileFormats\ → \BlackFormats\ in Bootstrap and SilentUpdateMode callers
• DrivelutionMiddleware remains excluded (requires net10.0; Core targets netstandard2.0)

Verification

• \dotnet build src/c#/GeneralUpdate.slnx\ → 0 errors, 0 warnings across all 11 projects
• All tests compile successfully

Closes #342