Add chat terminal sandbox smoke tests

[dileepyavan]

Summary

• add Linux and macOS smoke coverage for chat.agent.sandbox.enabled
• verify sandboxed terminal execution, workspace and temporary-directory writes, outside-workspace read/write behavior, and default network denial
• use deterministic mock LLM tool calls and a local HTTP probe rather than external network dependencies
• register the suite for desktop, non-remote smoke runs

Validation

• cd test/smoke && npm run compile
• npm run precommit

The end-to-end suite has not completed successfully in the current local environment because Chat did not become ready during the smoke-test warm-up, so this is opened as a draft for CI validation and iteration.

[Copilot]

Pull request overview

Adds a new Electron smoke-test suite to exercise the Chat terminal sandbox (chat.agent.sandbox.enabled) on Linux/macOS using deterministic mock-LLM tool calls plus a local HTTP probe, and wires the suite into the desktop (non-remote) smoke run.

Changes:

• Register a new “Chat Sandbox” smoke-test suite in the main Electron smoke runner.
• Add end-to-end sandbox validations for: terminal execution, workspace vs outside-workspace write behavior, outside-workspace reads, TMPDIR writes, and default network denial.
• Use a mock LLM server + echo-last-message tool-result echoing to assert against the tool output payload.

Show a summary per file

File	Description
test/smoke/src/main.ts	Registers the new Chat Sandbox smoke suite for Electron non-remote runs.
test/smoke/src/areas/chat/chatSandbox.test.ts	New Linux/macOS smoke suite that drives chat tool calls to validate terminal sandbox filesystem + network restrictions.

Review details

• Files reviewed: 2/2 changed files
• Comments generated: 1
• Review effort level: Low