Antigravity usage after #24073: an old agy can still spend a billed turn on /usage, and the bar still demands Gemini OAuth #24282

Overview

#24073 landed the agy-CLI quota read (closing #9122, #22511, #14515). Two gaps from the original fix (#22055, superseded) survived the landing:

1. No version gate before the quota read. agy older than 1.1.11 answers -p /usage as a prompt — a billed model turn — instead of a quota report. The current fetcher's only defense is the model-turn latch, which triggers after a turn has already been spent. Every user on an old agy pays one turn per Orca run to discover the same fact.

2. The Antigravity bar is still gated on Gemini CLI OAuth. status-bar-provider-visibility.ts still requires geminiCliOAuthEnabled for antigravityUsageConfigured — a leftover from when the Antigravity snapshot mirrored the Gemini fetch. Since fix(rate-limits): read real Antigravity quota from the agy CLI, not the Gemini mirror #24073 the snapshot comes from the agy CLI probe and needs no Gemini OAuth, so an Antigravity user who never opted into Gemini CLI OAuth never sees their quota.

Reproduction

1. Install agy < 1.1.11 (or 1.1.11-rc.1), sign in, open the usage roster → each refresh cycle runs agy -p /usage, spending quota.
2. With agy installed and the Antigravity status item checked but geminiCliOAuthEnabled off → the Antigravity segment never appears.

Expected

• agy --version is probed before every quota read; below 1.1.11 (prereleases included) /usage never runs and the bar says to update agy.
• The Antigravity bar's durable signal is the checked item + PATH detection, with no Gemini OAuth requirement.