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/web/web_read_json/factory.py

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

workflow/plugins/python/web/web_read_json/package.json

@@ -1,13 +1,16 @@
 {
   "name": "@metabuilder/web_read_json",
   "version": "1.0.0",
-  "description": "web_read_json plugin",
+  "description": "Read JSON file",
   "author": "MetaBuilder",
   "license": "MIT",
   "keywords": ["web", "workflow", "plugin"],
   "main": "web_read_json.py",
+  "files": ["web_read_json.py", "factory.py"],
   "metadata": {
     "plugin_type": "web.read_json",
-    "category": "web"
+    "category": "web",
+    "class": "WebReadJson",
+    "entrypoint": "execute"
   }
 }

workflow/plugins/python/web/web_read_json/web_read_json.py

@@ -1,21 +1,31 @@
 """Workflow plugin: read JSON file."""
+
 import json
 from pathlib import Path
 
+from ...base import NodeExecutor
 
-def run(_runtime, inputs):
+
+class WebReadJson(NodeExecutor):
     """Read JSON file."""
-    path = inputs.get("path")
-    if not path:
-        return {"error": "path is required"}
 
-    path_obj = Path(path)
-    if not path_obj.exists():
-        return {"result": {}}
+    node_type = "web.read_json"
+    category = "web"
+    description = "Read JSON file"
 
-    try:
-        json_data = json.loads(path_obj.read_text(encoding="utf-8"))
-    except json.JSONDecodeError:
-        return {"result": {}}
+    def execute(self, inputs, runtime=None):
+        """Read JSON file."""
+        path = inputs.get("path")
+        if not path:
+            return {"error": "path is required"}
 
-    return {"result": json_data}
+        path_obj = Path(path)
+        if not path_obj.exists():
+            return {"result": {}}
+
+        try:
+            json_data = json.loads(path_obj.read_text(encoding="utf-8"))
+        except json.JSONDecodeError:
+            return {"result": {}}
+
+        return {"result": json_data}