- parser.zig: collect and merge all class values (shorthand and parenthesized) into single attribute
- Filter out empty, null, undefined class values during parsing
- Reverted redundant merging logic from codegen.zig, template.zig, zig_codegen.zig
- Added documentation about shared AST consumers relationship
- codegen.zig: collect class values and output as single merged attribute
- template.zig: respect quoted flag to prevent data lookup for static class values
- Added tests for multiple class merging scenarios
