Remove bundled @github/copilot from release tarball

## Problem

The CE 1.2.0-rc.1 tarball includes `@github/copilot*` packages in `node_modules/` which add **237 MB** to the release artifact:

```
152M node_modules/@github/copilot-linuxmusl-x64/
82M node_modules/@github/copilot/
3.0M node_modules/@github/copilot-sdk/
```

This was introduced by VS Code 1.119.x's built-in Copilot integration (ref: https://code.visualstudio.com/updates/v1_116).

Since SageMaker Code Editor removes all Copilot-related features for compliance/branding/legal reasons, these dependencies should also be excluded from the tarball.

## Impact

- Conda package size increased from ~50 MB (CE 1.0.13) to ~150 MB (CE 1.2.0-rc.1)
- The `@github/copilot*` packages account for nearly all of the increase
- Unnecessary binary bloat shipped to every SMD customer

## Proposed Fix

Exclude `@github/copilot*` from `node_modules/` in the tarball creation script (`scripts/create_code_editor_tarball.sh` or equivalent).

```bash
rm -rf vscode-reh-web-linux-x64/node_modules/@github
```

## Workaround

The conda-forge feedstock can strip it during packaging in `build.sh` as an interim fix.

Read scripts/create_code_editor_tarball.sh, or the equivalent tarball creation script, and trace how node_modules is assembled. Run the packaging process, verify the resulting tarball contains no @github/copilot packages, and confirm the unnecessary artifact size is removed.

Written by the indexing model from the issue text.