fix: merge multiple class attributes in zig_codegen (compiled templates)

- zig_codegen.zig: collect and merge class values in both static and dynamic attribute paths
- Completes the fix for multiple classes (.a.b -> class="a b") across all rendering modes

build.zig.zon

@@ -1,6 +1,6 @@
 .{
     .name = .pugz,
-    .version = "0.3.4",
+    .version = "0.3.5",
     .fingerprint = 0x822db0790e17621d, // Changing this has security and trust implications.
     .minimum_zig_version = "0.15.2",
     .dependencies = .{},

src/tpl_compiler/zig_codegen.zig

@@ -224,7 +224,19 @@ pub const Codegen = struct {
 
         if (!has_dynamic_attrs) {
             // All static attributes - include in buffer
+            // Collect class values to merge into single attribute
+            var class_values = std.ArrayListUnmanaged([]const u8){};
+            defer class_values.deinit(self.allocator);
+
             for (tag.attrs.items) |attr| {
+                if (std.mem.eql(u8, attr.name, "class")) {
+                    // Collect class values for merging
+                    if (attr.val) |val| {
+                        if (val.len > 0) {
+                            try class_values.append(self.allocator, val);
+                        }
+                    }
+                } else {
                     try self.addStatic(" ");
                     try self.addStatic(attr.name);
                     if (attr.val) |val| {
@@ -240,12 +252,41 @@ pub const Codegen = struct {
                         }
                     }
                 }
+            }
+
+            // Output merged class attribute
+            if (class_values.items.len > 0) {
+                try self.addStatic(" class=\"");
+                for (class_values.items, 0..) |class_val, i| {
+                    if (i > 0) {
+                        try self.addStatic(" ");
+                    }
+                    try self.addStatic(class_val);
+                }
+                try self.addStatic("\"");
+            }
+
             try self.addStatic(">");
         } else {
             // Flush static content before dynamic attributes (this closes any open string)
             try self.flushStaticBuffer();
 
+            // Collect static class values for merging
+            var static_class_values = std.ArrayListUnmanaged([]const u8){};
+            defer static_class_values.deinit(self.allocator);
+
+            // First pass: output non-class attributes
             for (tag.attrs.items) |attr| {
+                // Skip class attributes - handle them separately
+                if (std.mem.eql(u8, attr.name, "class")) {
+                    if (attr.val) |val| {
+                        if (val.len > 0) {
+                            try static_class_values.append(self.allocator, val);
+                        }
+                    }
+                    continue;
+                }
+
                 if (attr.val) |val| {
                     // Quoted values are always static, unquoted can be field references
                     if (!attr.quoted and self.isDataFieldReference(val)) {
@@ -303,6 +344,19 @@ pub const Codegen = struct {
                 }
             }
 
+            // Output merged class attribute
+            if (static_class_values.items.len > 0) {
+                try self.writeIndent();
+                try self.write("try buf.appendSlice(allocator, \" class=\\\"");
+                for (static_class_values.items, 0..) |class_val, i| {
+                    if (i > 0) {
+                        try self.write(" ");
+                    }
+                    try self.writeEscaped(class_val);
+                }
+                try self.writeLine("\\\"\");");
+            }
+
             try self.writeIndent();
             try self.writeLine("try buf.appendSlice(allocator, \">\");");
         }