refactor(workflow): convert all plugins to class/struct + factory pattern

- Python: class extending NodeExecutor + factory.py (80+ plugins)
- TypeScript: class implements NodeExecutor + factory.ts (7 groups, 116 classes)
- Go: struct with methods + factory.go (36 plugins)
- Rust: struct impl NodeExecutor trait + factory.rs (54 plugins)
- Mojo: struct + factory.mojo (11 plugins)

All package.json files now include:
- files array listing source files
- metadata.class/struct field
- metadata.entrypoint field

This enables a unified plugin loading system across all languages
with no import side effects (Spring-style DI pattern).

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

workflow/plugins/python/convert/convert_parse_json/convert_parse_json.py

@@ -1,13 +1,21 @@
 """Workflow plugin: parse JSON string."""
+
 import json
 
+from ...base import NodeExecutor
 
-def run(_runtime, inputs):
+
+class ConvertParseJson(NodeExecutor):
     """Parse JSON string to object."""
-    text = inputs.get("text", "")
 
-    try:
-        result = json.loads(text)
-        return {"result": result}
-    except json.JSONDecodeError as e:
-        return {"result": None, "error": str(e)}
+    node_type = "convert.parseJson"
+    category = "convert"
+    description = "Parse JSON string to object"
+
+    def execute(self, inputs, runtime=None):
+        text = inputs.get("text", "")
+        try:
+            result = json.loads(text)
+            return {"result": result}
+        except json.JSONDecodeError as e:
+            return {"result": None, "error": str(e)}

workflow/plugins/python/convert/convert_parse_json/factory.py

@@ -0,0 +1,7 @@
+"""Factory for ConvertParseJson plugin."""
+
+from .convert_parse_json import ConvertParseJson
+
+
+def create():
+    return ConvertParseJson()

workflow/plugins/python/convert/convert_parse_json/package.json

@@ -1,13 +1,16 @@
 {
   "name": "@metabuilder/convert_parse_json",
   "version": "1.0.0",
-  "description": "convert_parse_json plugin",
+  "description": "Parse JSON string to object",
   "author": "MetaBuilder",
   "license": "MIT",
   "keywords": ["convert", "workflow", "plugin"],
   "main": "convert_parse_json.py",
+  "files": ["convert_parse_json.py", "factory.py"],
   "metadata": {
-    "plugin_type": "convert.parse_json",
-    "category": "convert"
+    "plugin_type": "convert.parseJson",
+    "category": "convert",
+    "class": "ConvertParseJson",
+    "entrypoint": "execute"
   }
 }