docs: comprehensive documentation updates and modernization

- Update BUILDING.md with current build system information
- Modernize various README files across the project
- Update CHANGELOG.md with recent changes
- Improve documentation consistency and formatting
- Update platform-specific documentation (iOS, Electron, Docker)
- Enhance test documentation and build guides

doc/database-migration-guide.md

@@ -294,6 +294,7 @@ const result = await this.$db("SELECT * FROM contacts WHERE did = ?", [accountDi
 ```
 
 This provides:
+
 - **Caching**: Automatic caching for performance
 - **Error Handling**: Consistent error handling
 - **Type Safety**: Enhanced TypeScript integration