fix: escape quotes in backtick strings and merge duplicate class attributes

- HTML-escape double quotes as " in backtick template literals for valid attribute values
- Merge shorthand classes (.alert) with class attribute values instead of emitting duplicates
- Handle string concatenation expressions in class attributes (e.g., class="btn btn-" + type)

.gitignore

@@ -6,7 +6,7 @@ zig-cache/
 node_modules
 
 # compiled template file
-generated.zig
+#generated.zig
 
 # IDE
 .vscode/