feat(code-editor): InlineHints — count references from decompiled external assemblies

[abbaye]

Summary

CodeLens reference counts currently cover only source files in the solution workspace. References inside external/NuGet/GAC assemblies referenced by the project are not counted.

Context

A TODO has been placed in CodeLensService.ComputeLensData() (after the workspace scan loop) marking the exact insertion point for this feature.

Proposed Approach

1. For each project in the solution, resolve the list of referenced assembly paths (<Reference>, <PackageReference>, project-to-project refs)
2. For each assembly, decompile to C# skeleton text using AssemblyAnalysisEngine + CSharpSkeletonEmitter (already available in WpfHexEditor.Core.AssemblyAnalysis)
3. Feed the decompiled text into a per-assembly cache bucket within WorkspaceFileCache, keyed by assembly identity (name + version + culture + public key token) to avoid re-decompiling on every lens refresh
4. Run the same CountWholeWordOccurrencesInText() scan on the decompiled lines and add to the count

Acceptance Criteria

• CreateProviderWithData defined in project A shows +N references when called from an assembly B that references project A
• Cache is invalidated when the referenced assembly is rebuilt or replaced on disk
• Decompilation runs entirely on a background thread; no UI freeze
• Falls back gracefully (0 external refs) if decompilation fails

Related

• bug(code-editor): InlineHints reference count shows current-file only — WorkspaceFileCache not re-triggered after solution load #195 (CodeLens race condition fix — prerequisite)
• feat(assembly-explorer): DecompilerService emits skeleton stubs only — wire real decompiler backend (ILSpy) #188 (ILSpy decompiler backend — may be useful here)
• Sources/WpfHexEditor.Editor.CodeEditor/Services/CodeLensService.cs — TODO at line ~190
• Sources/WpfHexEditor.Core.AssemblyAnalysis/ — CSharpSkeletonEmitter + AssemblyAnalysisEngine

[abbaye]

Note: Renamed → following trademark cleanup in commit ac31aa89. The feature itself is unchanged: count symbol references including those resolved from decompiled external assemblies.