feat(editor): affine extension provider and manager (#11822)

Closes: BS-3186

# @blocksuite/affine-ext-loader

Blocksuite extension loader system for AFFiNE, providing a structured way to manage and load extensions in different contexts.

## Usage

### Basic Extension Provider

```typescript
import { BaseExtensionProvider } from '@blocksuite/affine-ext-loader';
import { z } from 'zod';

// Create a custom provider with options
class MyProvider extends BaseExtensionProvider<'my-scope', { enabled: boolean }> {
  name = 'MyProvider';

  schema = z.object({
    enabled: z.boolean(),
  });

  setup(context: Context<'my-scope'>, options?: { enabled: boolean }) {
    super.setup(context, options);
    // Custom setup logic
  }
}
```

### Store Extensions

```typescript
import { StoreExtensionProvider, StoreExtensionManager } from '@blocksuite/affine-ext-loader';
import { z } from 'zod';

// Create a store provider with custom options
class MyStoreProvider extends StoreExtensionProvider<{ cacheSize: number }> {
  override name = 'MyStoreProvider';

  override schema = z.object({
    cacheSize: z.number().min(0),
  });

  override setup(context: StoreExtensionContext, options?: { cacheSize: number }) {
    super.setup(context, options);
    context.register([Ext1, Ext2, Ext3]);
  }
}

// Create and use the store extension manager
const manager = new StoreExtensionManager([MyStoreProvider]);
manager.configure(MyStoreProvider, { cacheSize: 100 });
const extensions = manager.get('store');
```

### View Extensions

```typescript
import { ViewExtensionProvider, ViewExtensionManager } from '@blocksuite/affine-ext-loader';
import { z } from 'zod';

// Create a view provider with custom options
class MyViewProvider extends ViewExtensionProvider<{ theme: string }> {
  override name = 'MyViewProvider';

  override schema = z.object({
    theme: z.enum(['light', 'dark']),
  });

  override setup(context: ViewExtensionContext, options?: { theme: string }) {
    super.setup(context, options);

    context.register([CommonExt]);
    if (context.scope === 'page') {
      context.register([PageExt]);
    } else if (context.scope === 'edgeless') {
      context.register([EdgelessExt]);
    }
    if (options?.theme === 'dark') {
      context.register([DarkModeExt]);
    }
  }

  // Override effect to run one-time initialization logic
  override effect() {
    // This will only run once per provider class
    console.log('Initializing MyViewProvider');
    // Register lit elements
    this.registerLitElements();
  }
}

// Create and use the view extension manager
const manager = new ViewExtensionManager([MyViewProvider]);
manager.configure(MyViewProvider, { theme: 'dark' });

// Get extensions for different view scopes
const pageExtensions = manager.get('page');
const edgelessExtensions = manager.get('edgeless');
```

### One-time Initialization with Effect

View extensions support one-time initialization through the `effect` method. This method is called automatically during setup, but only once per provider class. It's useful for:

- Initializing global state
- Registering lit elements
- Setting up shared resources

```typescript
class MyViewProvider extends ViewExtensionProvider {
  override effect() {
    // This will only run once, even if multiple instances are created
    initializeGlobalState();
    registerLitElements();
    setupGlobalEventListeners();
  }
}
```

### Available View Scopes

The view extension system supports the following scopes:

- `page` - Standard page view
- `edgeless` - Edgeless (whiteboard) view
- `preview-page` - Page preview view
- `preview-edgeless` - Edgeless preview view
- `mobile-page` - Mobile page view
- `mobile-edgeless` - Mobile edgeless view

### Extension Configuration

Extensions can be configured using the `configure` method:

```typescript
// Set configuration directly
manager.configure(MyProvider, { enabled: true });

// Update configuration using a function
manager.configure(MyProvider, prev => {
  if (!prev) return prev;
  return {
    ...prev,
    enabled: !prev.enabled,
  };
});

// Remove configuration
manager.configure(MyProvider, undefined);
```

### Dependency Injection

Both store and view extension managers support dependency injection:

```typescript
// Access the manager through the di container
const viewManager = std.get(ViewExtensionManagerIdentifier);
const pagePreviewExtension = viewManager.get('preview-page');
```

blocksuite/affine/ext-loader/README.md

@@ -0,0 +1,132 @@
+# @blocksuite/affine-ext-loader
+
+Blocksuite extension loader system for AFFiNE, providing a structured way to manage and load extensions in different contexts.
+
+## Usage
+
+### Basic Extension Provider
+
+```typescript
+import { BaseExtensionProvider } from '@blocksuite/affine-ext-loader';
+import { z } from 'zod';
+
+// Create a custom provider with options
+class MyProvider extends BaseExtensionProvider<'my-scope', { enabled: boolean }> {
+  name = 'MyProvider';
+
+  schema = z.object({
+    enabled: z.boolean(),
+  });
+
+  setup(context: Context<'my-scope'>, options?: { enabled: boolean }) {
+    super.setup(context, options);
+    // Custom setup logic
+  }
+}
+```
+
+### Store Extensions
+
+```typescript
+import { StoreExtensionProvider, StoreExtensionManager } from '@blocksuite/affine-ext-loader';
+import { z } from 'zod';
+
+// Create a store provider with custom options
+class MyStoreProvider extends StoreExtensionProvider<{ cacheSize: number }> {
+  override name = 'MyStoreProvider';
+
+  override schema = z.object({
+    cacheSize: z.number().min(0),
+  });
+
+  override setup(context: StoreExtensionContext, options?: { cacheSize: number }) {
+    super.setup(context, options);
+    context.register([Ext1, Ext2, Ext3]);
+  }
+}
+
+// Create and use the store extension manager
+const manager = new StoreExtensionManager([MyStoreProvider]);
+manager.configure(MyStoreProvider, { cacheSize: 100 });
+const extensions = manager.get('store');
+```
+
+### View Extensions
+
+```typescript
+import { ViewExtensionProvider, ViewExtensionManager } from '@blocksuite/affine-ext-loader';
+import { z } from 'zod';
+
+// Create a view provider with custom options
+class MyViewProvider extends ViewExtensionProvider<{ theme: string }> {
+  override name = 'MyViewProvider';
+
+  override schema = z.object({
+    theme: z.enum(['light', 'dark']),
+  });
+
+  override setup(context: ViewExtensionContext, options?: { theme: string }) {
+    super.setup(context, options);
+
+    context.register([CommonExt]);
+    if (context.scope === 'page') {
+      context.register([PageExt]);
+    } else if (context.scope === 'edgeless') {
+      context.register([EdgelessExt]);
+    }
+    if (options?.theme === 'dark') {
+      context.register([DarkModeExt]);
+    }
+  }
+}
+
+// Create and use the view extension manager
+const manager = new ViewExtensionManager([MyViewProvider]);
+manager.configure(MyViewProvider, { theme: 'dark' });
+
+// Get extensions for different view scopes
+const pageExtensions = manager.get('page');
+const edgelessExtensions = manager.get('edgeless');
+```
+
+### Available View Scopes
+
+The view extension system supports the following scopes:
+
+- `page` - Standard page view
+- `edgeless` - Edgeless (whiteboard) view
+- `preview-page` - Page preview view
+- `preview-edgeless` - Edgeless preview view
+- `mobile-page` - Mobile page view
+- `mobile-edgeless` - Mobile edgeless view
+
+### Extension Configuration
+
+Extensions can be configured using the `configure` method:
+
+```typescript
+// Set configuration directly
+manager.configure(MyProvider, { enabled: true });
+
+// Update configuration using a function
+manager.configure(MyProvider, prev => {
+  if (!prev) return prev;
+  return {
+    ...prev,
+    enabled: !prev.enabled,
+  };
+});
+
+// Remove configuration
+manager.configure(MyProvider, undefined);
+```
+
+### Dependency Injection
+
+Both store and view extension managers support dependency injection:
+
+```typescript
+// Access the manager through the di container
+const viewManager = std.get(ViewExtensionManagerIdentifier);
+const pagePreviewExtension = viewManager.get('preview-page');
+```