feat(blueprint): refactor BlueprintComponent as proper ECS Component (#433)

* feat(blueprint): refactor BlueprintComponent as proper ECS Component

- Convert BlueprintComponent from interface to actual ECS Component class
- Add ready-to-use BlueprintSystem that extends EntitySystem
- Remove deprecated legacy APIs (createBlueprintSystem, etc.)
- Update all blueprint documentation (Chinese & English)
- Simplify user API: just add BlueprintSystem and BlueprintComponent

BREAKING CHANGE: BlueprintComponent is now a class extending Component,
not an interface. Use `new BlueprintComponent()` instead of
`createBlueprintComponentData()`.

* chore(blueprint): add changeset for ECS component refactor

* fix(node-editor): fix connections not rendering when node is collapsed

- getPinPosition now returns node header position when pin element is not found
- Added collapsedNodesKey to force re-render connections after collapse/expand
- Input pins connect to left side, output pins to right side of collapsed nodes

* chore(node-editor): add changeset for collapse connection fix

* feat(blueprint): add Add Component nodes for entity-component creation

- Add type-specific Add_ComponentName nodes via ComponentNodeGenerator
- Add generic ECS_AddComponent node for dynamic component creation
- Add ExecutionContext.getComponentClass() for component lookup
- Add registerComponentClass() helper for manual component registration
- Each Add node supports initial property values from @BlueprintProperty

* docs: update changeset with Add Component feature

* feat(blueprint): improve event nodes with Self output and auto-create BeginPlay

- Event Begin Play now outputs Self entity
- Event Tick now outputs Self entity + Delta Seconds
- Event End Play now outputs Self entity
- createEmptyBlueprint() now includes Event Begin Play by default
- Added menuPath to all event nodes for better organization

packages/framework/blueprint/src/runtime/ExecutionContext.ts

@@ -3,9 +3,10 @@
  * 执行上下文 - 蓝图执行的运行时上下文
  */
 
-import type { Entity, IScene } from '@esengine/ecs-framework';
+import type { Entity, IScene, Component } from '@esengine/ecs-framework';
 import { BlueprintNode, BlueprintConnection } from '../types/nodes';
 import { BlueprintAsset } from '../types/blueprint';
+import { getRegisteredBlueprintComponents } from '../registry/BlueprintDecorators';
 
 /**
  * Result of node execution
@@ -72,6 +73,9 @@ export class ExecutionContext {
     /** Global variables (shared) (全局变量，共享) */
     private static _globalVariables: Map<string, unknown> = new Map();
 
+    /** Component class registry (组件类注册表) */
+    private static _componentRegistry: Map<string, new () => Component> = new Map();
+
     /** Node output cache for current execution (当前执行的节点输出缓存) */
     private _outputCache: Map<string, Record<string, unknown>> = new Map();
 
@@ -267,4 +271,49 @@ export class ExecutionContext {
     static clearGlobalVariables(): void {
         ExecutionContext._globalVariables.clear();
     }
+
+    /**
+     * Get a component class by name
+     * 通过名称获取组件类
+     *
+     * @zh 首先检查 @BlueprintExpose 装饰的组件，然后检查手动注册的组件
+     * @en First checks @BlueprintExpose decorated components, then manually registered ones
+     */
+    getComponentClass(typeName: string): (new () => Component) | undefined {
+        // First check registered blueprint components
+        const blueprintComponents = getRegisteredBlueprintComponents();
+        for (const [componentClass, metadata] of blueprintComponents) {
+            if (metadata.componentName === typeName ||
+                componentClass.name === typeName) {
+                return componentClass as new () => Component;
+            }
+        }
+
+        // Then check manual registry
+        return ExecutionContext._componentRegistry.get(typeName);
+    }
+
+    /**
+     * Register a component class for dynamic creation
+     * 注册组件类以支持动态创建
+     */
+    static registerComponentClass(typeName: string, componentClass: new () => Component): void {
+        ExecutionContext._componentRegistry.set(typeName, componentClass);
+    }
+
+    /**
+     * Unregister a component class
+     * 取消注册组件类
+     */
+    static unregisterComponentClass(typeName: string): void {
+        ExecutionContext._componentRegistry.delete(typeName);
+    }
+
+    /**
+     * Get all registered component classes
+     * 获取所有已注册的组件类
+     */
+    static getRegisteredComponentClasses(): Map<string, new () => Component> {
+        return new Map(ExecutionContext._componentRegistry);
+    }
 }