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/test/test_assert_equals/factory.py

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

workflow/plugins/python/test/test_assert_equals/package.json

@@ -1,13 +1,16 @@
 {
   "name": "@metabuilder/test_assert_equals",
   "version": "1.0.0",
-  "description": "test_assert_equals plugin",
+  "description": "Assert that two values are equal",
   "author": "MetaBuilder",
   "license": "MIT",
   "keywords": ["test", "workflow", "plugin"],
   "main": "test_assert_equals.py",
+  "files": ["test_assert_equals.py", "factory.py"],
   "metadata": {
     "plugin_type": "test.assert_equals",
-    "category": "test"
+    "category": "test",
+    "class": "TestAssertEquals",
+    "entrypoint": "execute"
   }
 }

workflow/plugins/python/test/test_assert_equals/test_assert_equals.py

@@ -1,26 +1,35 @@
 """Workflow plugin: assert two values are equal."""
 
+from ...base import NodeExecutor
 
-def run(_runtime, inputs):
+
+class TestAssertEquals(NodeExecutor):
     """Assert that two values are equal."""
-    actual = inputs.get("actual")
-    expected = inputs.get("expected")
-    message = inputs.get("message", "")
 
-    passed = actual == expected
+    node_type = "test.assert_equals"
+    category = "test"
+    description = "Assert that two values are equal"
+
+    def execute(self, inputs, runtime=None):
+        """Assert that two values are equal."""
+        actual = inputs.get("actual")
+        expected = inputs.get("expected")
+        message = inputs.get("message", "")
+
+        passed = actual == expected
+
+        if not passed:
+            error_msg = f"Assertion failed: {message}" if message else "Assertion failed"
+            error_msg += f"\n  Expected: {expected}\n  Actual: {actual}"
+            return {
+                "passed": False,
+                "error": error_msg,
+                "expected": expected,
+                "actual": actual
+            }
 
-    if not passed:
-        error_msg = f"Assertion failed: {message}" if message else "Assertion failed"
-        error_msg += f"\n  Expected: {expected}\n  Actual: {actual}"
         return {
-            "passed": False,
-            "error": error_msg,
+            "passed": True,
             "expected": expected,
             "actual": actual
         }
-
-    return {
-        "passed": True,
-        "expected": expected,
-        "actual": actual
-    }