feat: add CLI update checker (#223)

* feat: add CLI update checker

Check for newer grok-dev releases when the interactive CLI starts and surface them through a startup modal, home banner, and update commands.

* ci: increase PR commit scan curl timeout to 300s

.github/workflows/pr-commit-security-scan.yml

@@ -42,7 +42,7 @@ jobs:
             commit_url="https://github.com/${REPO}/commit/${sha}"
 
             response="$(
-              curl -sfL --max-time 110 \
+              curl -sfL --max-time 300 \
                 "https://api.brin.sh/commit/${REPO}@${sha}?details=true&mode=full&tolerance=conservative" \
                 || echo '{}'
             )"