- Add iconv-lite dependency for encoding conversion
- Create src/utils/fileEncoding.ts utility that:
- Gets file encoding from VSCode settings (files.encoding)
- Provides readFileWithEncoding() and writeFileWithEncoding() functions
- Includes fallback to UTF-8 if encoding conversion fails
- Update DiffViewProvider.ts to use encoding-aware file operations
- Update ApplyPatchTool.ts to use encoding-aware file operations
- Add comprehensive tests for the encoding utility
Fixes#11002
