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/var/var_delete/factory.py

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

workflow/plugins/python/var/var_delete/package.json

@@ -1,13 +1,16 @@
 {
   "name": "@metabuilder/var_delete",
   "version": "1.0.0",
-  "description": "var_delete plugin",
+  "description": "Delete variable from workflow store",
   "author": "MetaBuilder",
   "license": "MIT",
   "keywords": ["var", "workflow", "plugin"],
   "main": "var_delete.py",
+  "files": ["var_delete.py", "factory.py"],
   "metadata": {
     "plugin_type": "var.delete",
-    "category": "var"
+    "category": "var",
+    "class": "VarDelete",
+    "entrypoint": "execute"
   }
 }

workflow/plugins/python/var/var_delete/var_delete.py

@@ -1,15 +1,24 @@
 """Workflow plugin: delete variable from workflow store."""
 
+from ...base import NodeExecutor
 
-def run(runtime, inputs):
-    """Delete variable from workflow store."""
-    key = inputs.get("key")
 
-    if key is None:
-        return {"result": False, "deleted": False, "error": "key is required"}
+class VarDelete(NodeExecutor):
+    """Delete a variable from the workflow store."""
 
-    if key in runtime.store:
-        del runtime.store[key]
-        return {"result": True, "deleted": True}
+    node_type = "var.delete"
+    category = "var"
+    description = "Delete variable from workflow store"
 
-    return {"result": False, "deleted": False}
+    def execute(self, inputs, runtime=None):
+        """Delete variable from workflow store."""
+        key = inputs.get("key")
+
+        if key is None:
+            return {"result": False, "deleted": False, "error": "key is required"}
+
+        if key in runtime.store:
+            del runtime.store[key]
+            return {"result": True, "deleted": True}
+
+        return {"result": False, "deleted": False}

workflow/plugins/python/var/var_exists/factory.py

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

workflow/plugins/python/var/var_exists/package.json

@@ -1,13 +1,16 @@
 {
   "name": "@metabuilder/var_exists",
   "version": "1.0.0",
-  "description": "var_exists plugin",
+  "description": "Check if variable exists in workflow store",
   "author": "MetaBuilder",
   "license": "MIT",
   "keywords": ["var", "workflow", "plugin"],
   "main": "var_exists.py",
+  "files": ["var_exists.py", "factory.py"],
   "metadata": {
     "plugin_type": "var.exists",
-    "category": "var"
+    "category": "var",
+    "class": "VarExists",
+    "entrypoint": "execute"
   }
 }

workflow/plugins/python/var/var_exists/var_exists.py

@@ -1,13 +1,22 @@
 """Workflow plugin: check if variable exists in workflow store."""
 
+from ...base import NodeExecutor
 
-def run(runtime, inputs):
-    """Check if variable exists in workflow store."""
-    key = inputs.get("key")
 
-    if key is None:
-        return {"result": False, "error": "key is required"}
+class VarExists(NodeExecutor):
+    """Check if a variable exists in the workflow store."""
 
-    exists = key in runtime.store
+    node_type = "var.exists"
+    category = "var"
+    description = "Check if variable exists in workflow store"
 
-    return {"result": exists}
+    def execute(self, inputs, runtime=None):
+        """Check if variable exists in workflow store."""
+        key = inputs.get("key")
+
+        if key is None:
+            return {"result": False, "error": "key is required"}
+
+        exists = key in runtime.store
+
+        return {"result": exists}

workflow/plugins/python/var/var_get/factory.py

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

workflow/plugins/python/var/var_get/package.json

@@ -1,13 +1,16 @@
 {
   "name": "@metabuilder/var_get",
   "version": "1.0.0",
-  "description": "var_get plugin",
+  "description": "Get variable from workflow store",
   "author": "MetaBuilder",
   "license": "MIT",
   "keywords": ["var", "workflow", "plugin"],
   "main": "var_get.py",
+  "files": ["var_get.py", "factory.py"],
   "metadata": {
     "plugin_type": "var.get",
-    "category": "var"
+    "category": "var",
+    "class": "VarGet",
+    "entrypoint": "execute"
   }
 }

workflow/plugins/python/var/var_get/var_get.py

@@ -1,15 +1,24 @@
 """Workflow plugin: get variable from workflow store."""
 
+from ...base import NodeExecutor
 
-def run(runtime, inputs):
-    """Get variable value from workflow store."""
-    key = inputs.get("key")
-    default = inputs.get("default")
 
-    if key is None:
-        return {"result": default, "exists": False, "error": "key is required"}
+class VarGet(NodeExecutor):
+    """Get a variable value from the workflow store."""
 
-    exists = key in runtime.store
-    value = runtime.store.get(key, default)
+    node_type = "var.get"
+    category = "var"
+    description = "Get variable from workflow store"
 
-    return {"result": value, "exists": exists}
+    def execute(self, inputs, runtime=None):
+        """Get variable value from workflow store."""
+        key = inputs.get("key")
+        default = inputs.get("default")
+
+        if key is None:
+            return {"result": default, "exists": False, "error": "key is required"}
+
+        exists = key in runtime.store
+        value = runtime.store.get(key, default)
+
+        return {"result": value, "exists": exists}

workflow/plugins/python/var/var_set/factory.py

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

workflow/plugins/python/var/var_set/package.json

@@ -1,13 +1,16 @@
 {
   "name": "@metabuilder/var_set",
   "version": "1.0.0",
-  "description": "var_set plugin",
+  "description": "Set variable in workflow store",
   "author": "MetaBuilder",
   "license": "MIT",
   "keywords": ["var", "workflow", "plugin"],
   "main": "var_set.py",
+  "files": ["var_set.py", "factory.py"],
   "metadata": {
     "plugin_type": "var.set",
-    "category": "var"
+    "category": "var",
+    "class": "VarSet",
+    "entrypoint": "execute"
   }
 }

workflow/plugins/python/var/var_set/var_set.py

@@ -1,14 +1,23 @@
 """Workflow plugin: set variable in workflow store."""
 
+from ...base import NodeExecutor
 
-def run(runtime, inputs):
-    """Set variable value in workflow store."""
-    key = inputs.get("key")
-    value = inputs.get("value")
 
-    if key is None:
-        return {"result": None, "key": None, "error": "key is required"}
+class VarSet(NodeExecutor):
+    """Set a variable value in the workflow store."""
 
-    runtime.store[key] = value
+    node_type = "var.set"
+    category = "var"
+    description = "Set variable in workflow store"
 
-    return {"result": value, "key": key}
+    def execute(self, inputs, runtime=None):
+        """Set variable value in workflow store."""
+        key = inputs.get("key")
+        value = inputs.get("value")
+
+        if key is None:
+            return {"result": None, "key": None, "error": "key is required"}
+
+        runtime.store[key] = value
+
+        return {"result": value, "key": key}