Add Sample Explorer view implementation

[Copilot]

Implements a minimal "Sample Explorer" view demonstrating the workbench explorer pattern.

Implementation

• ViewPane: SampleExplorerView extends ViewPane with proper service injection
• Container: SampleExplorerViewPaneContainer registered in sidebar (order: 10, file-code icon)
• Registration: Workbench contribution at BlockStartup phase
• Integration: Added to workbench.common.main.ts imports

Structure

// Constants defined in common/
export const VIEWLET_ID = 'workbench.view.sampleExplorer';
export const VIEW_ID = 'workbench.sampleExplorer.view';

// View extends ViewPane with standard DI pattern
export class SampleExplorerView extends ViewPane {
  static readonly ID = VIEW_ID;
  static readonly NAME = localize('sampleExplorer', "Sample Explorer");
  
  protected override renderBody(container: HTMLElement): void {
    super.renderBody(container);
    container.textContent = localize('sampleExplorerContent', 
      "Sample Explorer - This is a new explorer implementation!");
  }
}

Files Added

• src/vs/workbench/contrib/sampleExplorer/ - Core implementation (7 files, 279 LOC)
• Unit tests verifying view constants and initialization
• README and ARCHITECTURE docs

Serves as reference implementation for custom explorer views. Ready for extension with tree widgets, renderers, and actions.

Original prompt

implement new explorer

The user has attached the following files as relevant context:

• .github/instructions/learnings.instructions.md
• .github/copilot-instructions.md
• .github/copilot-instructions.md

Created from VS Code via the GitHub Pull Request extension.

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