Verify README for v0.2.0 release

[rakyll]

[joycel-github]

• docs(readme): fix invalid harness in exec example #309 — fix invalid harness in exec example (base: main)
• docs(readme): refresh Antigravity setup, auth, and CLI usage #310 — refresh Antigravity setup, auth, and CLI usage (stacked on docs(readme): fix invalid harness in exec example #309)

More to come