fix: enforce removal of git terminal commands

[kbuffardi]

Summary

• Include the existing simulated-terminal Git removal regression suite in npm run test:e2e.
• Document that git status returns bash: git: command not found and that version control belongs in a native terminal.
• Preserve .git metadata detection and ordinary .git workspace visibility.

The terminal implementation cleanup itself (removing the help entry, completion, dispatcher, and handler) is already present in the base branch history; this PR ensures the behavior is covered by the aggregate suite and clearly documented.

Verification

• node --experimental-detect-module --test scripts/e2e-terminal-git-removal.test.mjs — 4 passed
• npm run lint — passed
• npm run test:e2e — 144 passed
• npm run build — passed; webpack emitted the repository's existing asset-size warnings
• Generated output no longer contains Basic git info for opened repo

Closes #49