Provider Usage v0.15.0

Provider headlines now show the most restrictive subscription window. A full five-hour allowance no longer hides an exhausted weekly allowance, including Muse Code. The navigation rail percentage and overview use the same provider figures, counting each provider once.

Adds Google Antigravity usage from the official CLI's read-only /usage report, with separate five-hour and weekly windows for Gemini and Claude/GPT models. Requires a registered acp-antigravity provider and a signed-in agy CLI on the primary machine. Authentication and refresh remain with Google's CLI.

Also includes the previously local v0.14.1 improvements to pooled quota sources, per-machine caches, reset inventory, and token accounting.

Validation: 93 tests passed, TypeScript check passed, BB plugin build passed. Verified live Muse weekly remaining and the recalculated navigation total.