fix: preserve @github/copilot/sdk/index.js during extension packaging

The .moduleignore rule stripped sdk/index.js from @github/copilot, which
is correct for app-level node_modules but breaks the built-in copilot
extension when built from source via packageCopilotExtensionStream.
The copilot extension externalizes @github/copilot in esbuild and needs
sdk/index.js at runtime for CLI sessions, agents, and model fetching.

Signed-off-by: Roman Nikitenko <rnikiten@redhat.com>
Assisted-by: Cursor AI

Author: RomanNikitenko

code/build/.moduleignore

@@ -215,7 +215,6 @@ zone.js/dist/**
 @xterm/xterm-addon-*/out-test/**
 
 # @github/copilot - strip unneeded binaries and files
-@github/copilot/sdk/index.js
 @github/copilot/prebuilds/**
 @github/copilot/clipboard/**
 @github/copilot/ripgrep/**