Add Cloud Agent development environment for the Server component - #2

Summary

Adds a repository-managed Cloud Agent environment (.cursor/environment.json) so this repo is usable in Cloud Agents, scoped to the Node/TypeScript Server/ component (the WebKit-hosted terminal and diffView bundles). The macOS/Xcode app targets require a macOS runner and are out of scope for Linux Cloud Agents.

⚠️ This PR is largely redundant

PR #4 already merged this same feature to main (commit 248ba95, "Add Cloud Agent environment config for Server component build"). The only net-new value this PR offers over main is the deterministic npm ci --force install (lockfile-based) in place of main's npm install --force.

Maintainer decision needed: either close this PR as superseded, or keep it only for the npm install → npm ci improvement.

Merge conflict resolution

Merged latest main. There was one conflict — an add/add on .cursor/environment.json (duplicate intent with PR #4). .github/workflows/github-actions-demo.yml from main merged cleanly.

Resolved as a superset (merge commit a492ba5):

• Kept main/Add Cloud Agent environment config for Server component #4's fuller config: name: "Copilot for Xcode", terminals "Server preview" (python3 -m http.server 8099), and ports: [8099].
• Adopted this branch's deterministic npm ci --force.

{
  "name": "Copilot for Xcode",
  "install": "cd Server && npm ci --force && npm run build",
  "terminals": [{ "name": "Server preview", "command": "cd Server/dist && python3 -m http.server 8099" }],
  "ports": [8099]
}

--force is required because Server/package.json pins darwin-only @github/copilot-language-server-darwin-* binaries as hard deps; on Linux plain npm ci fails EBADPLATFORM. The webpack bundles don't import those binaries. Note: npm ci requires Server/package-lock.json to stay in sync with package.json.

Validation (post-merge)

• .cursor/environment.json: valid JSON, no leftover conflict markers.
• cd Server && npm ci --force && npm run build → exit 0; webpack compiled (asset-size warnings only).
• Produced dist/terminal/terminal.js and dist/diffView/diffView.js.