fix: merge multiple class attributes into single attribute

- 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

docs/CLAUDE.md

@@ -12,6 +12,10 @@ Pugz is a Pug-like HTML template engine written in Zig 0.15.2. It compiles Pug t
 - When the user specifies a new rule, update this CLAUDE.md file to include it.
 - Code comments are required but must be meaningful, not bloated. Focus on explaining "why" not "what". Avoid obvious comments like "// increment counter" - instead explain complex logic, non-obvious decisions, or tricky edge cases.
 - **All documentation files (.md) must be saved to the `docs/` directory.** Do not create .md files in the root directory or examples directories - always place them in `docs/`.
+- **Publish command**: When user says "publish", do the following:
+  1. Bump the fix version (patch version in build.zig.zon)
+  2. Git commit with appropriate message
+  3. Git push to remote `origin` and remote `github`
 
 ## Build Commands