Implement KJNodes extension with new mappers and transform functions

- Added KJNodes mappers for JoinStrings, StringConstantMultiline, and EmptyLatentImagePresets.
- Introduced transform functions to handle string joining, string constants, and dimension extraction with optional inversion.
- Registered new mappers and logged successful registration for better traceability.

py/workflow/ext/kjnodes.py

@@ -0,0 +1,81 @@
+"""
+KJNodes mappers extension for ComfyUI workflow parsing
+"""
+import logging
+import re
+from typing import Dict, Any
+
+logger = logging.getLogger(__name__)
+
+# Import the mapper registration functions from the parent module
+from workflow.mappers import create_mapper, register_mapper
+
+# =============================================================================
+# Transform Functions
+# =============================================================================
+
+def transform_join_strings(inputs: Dict) -> str:
+    """Transform function for JoinStrings nodes"""
+    string1 = inputs.get("string1", "")
+    string2 = inputs.get("string2", "")
+    delimiter = inputs.get("delimiter", "")
+    return f"{string1}{delimiter}{string2}"
+
+def transform_string_constant(inputs: Dict) -> str:
+    """Transform function for StringConstant nodes"""
+    return inputs.get("string", "")
+
+def transform_empty_latent_presets(inputs: Dict) -> Dict:
+    """Transform function for EmptyLatentImagePresets nodes"""
+    dimensions = inputs.get("dimensions", "")
+    invert = inputs.get("invert", False)
+    
+    # Extract width and height from dimensions string
+    # Expected format: "width x height (ratio)" or similar
+    width = 0
+    height = 0
+    
+    if dimensions:
+        # Try to extract dimensions using regex
+        match = re.search(r'(\d+)\s*x\s*(\d+)', dimensions)
+        if match:
+            width = int(match.group(1))
+            height = int(match.group(2))
+    
+    # If invert is True, swap width and height
+    if invert and width and height:
+        width, height = height, width
+    
+    return {"width": width, "height": height, "size": f"{width}x{height}"}
+
+# =============================================================================
+# Register Mappers
+# =============================================================================
+
+# Define the mappers for KJNodes
+KJNODES_MAPPERS = {
+    "JoinStrings": {
+        "inputs_to_track": ["string1", "string2", "delimiter"],
+        "transform_func": transform_join_strings
+    },
+    "StringConstantMultiline": {
+        "inputs_to_track": ["string"],
+        "transform_func": transform_string_constant
+    },
+    "EmptyLatentImagePresets": {
+        "inputs_to_track": ["dimensions", "invert", "batch_size"],
+        "transform_func": transform_empty_latent_presets
+    }
+}
+
+# Register all KJNodes mappers
+for node_type, config in KJNODES_MAPPERS.items():
+    mapper = create_mapper(
+        node_type=node_type,
+        inputs_to_track=config["inputs_to_track"],
+        transform_func=config["transform_func"]
+    )
+    register_mapper(mapper)
+    logger.info(f"Registered KJNodes mapper for node type: {node_type}")
+
+logger.info(f"Loaded KJNodes extension with {len(KJNODES_MAPPERS)} mappers")