[QA] In-editor end-to-end smoke test for the .affine VS Code extension #139

Problem

The port of the VS Code extension from extension.ts to extension.affine (tracked in #63, unblocked by #35) is complete and mechanically verified: the .ts file is gone, package.json main points at ./out/extension.cjs, the --vscode-extension wiring (#90, #116) resolves the Vscode/VscodeLanguageClient imports, and tools/check-no-extension-ts.sh guards against regression.

The one acceptance item from #63 that cannot be proven from the repo tree is live-host behaviour: it needs a running VS Code extension host.

Acceptance criteria

Load the compiled ./out/extension.cjs in a real VS Code host and verify:

• Extension activates without error.
• All five commands register and run: affinescript.{check,eval,compile,format,restartLsp}.
• LSP client starts, attaches, and restartLsp cycles it cleanly.
• Disposables are cleaned up on deactivate (no leaked watchers/terminals).

Origin

Split out of #63 so that issue can close on its mechanically-verifiable criteria. Fold into the #104 publish QA pass if convenient rather than running standalone.

Dependencies

• [Repo] Port editors/vscode/src/extension.ts to .affine once #35 lands #63 (port — complete)
• Add Node-target backend + vscode-API bindings to enable .affine VS Code extensions #35 (Node-target backend — complete)
• Relates to Publish @hyperpolymath/affine-vscode to npm (eliminate vendoring) #104 (publish)