Add Antigravity CLI provider integration

[ahrorbeksoft]

What changed

Adds support for the Google Antigravity CLI (agy) as a provider harness in MonoCode:

• Implemented AntigravityAdapter and streaming protocol parser (antigravityProtocol.ts) handling sessions, assistant turns, tool calls, and user interruptions.
• Added model catalog discovery and provider metadata for Antigravity models.
• Integrated rate limit tracking and usage display.
• Added global skills discovery for Antigravity native skills.
• Added user inquiry / question answering handling.
• Added SVG icon and UI wiring across ModelPicker, Composer, and Settings.
• Full test coverage added for protocol, catalog, git helpers, rate limits, and skills.

Why

Allows MonoCode users to run agentic pair-programming workflows powered by the Google Antigravity CLI.

UI

• Added Antigravity icon in src/assets/providers/antigravity.svg
• Listed Antigravity in the model picker, settings provider list, and composer dropdowns when detected.

Checklist

• I ran npm run check
• This PR is small and focused
• I did not mix unrelated changes

[hardbeat920]

Thanks for putting this together @ahrorbeksoft, the integration is clearly a lot of work, and the direction makes sense.

However, I’m going to pause new harnesses for a bit, including this one. We still need to settle a few things on the providers we already ship (lifecycle, catalog/probes, usage, permissions/approvals, how slash commands and skills are wired). New adapters tend to copy whatever is there today, so if we land another one now we’ll freeze those inconsistencies in place.

Once those patterns are explicit and the existing harnesses follow them, Antigravity (and anything after it) should be much cheaper to add and review. Happy to revisit this PR then.

[ahrorbeksoft]

Thanks for the thoughtful feedback @hardbeat920, that makes complete sense!

Standardizing the lifecycle, catalog/probes, permissions, and skill wiring across existing harnesses first is definitely the right call. Antigravity's ACP/CLI side also still has a few evolving limitations and moving parts, so letting both sides settle will make integrating against the new abstractions much cleaner and easier to maintain.

Happy to pause this for now and revisit/rebase it once the standardized harness patterns land. Thanks again!

[hardbeat920]

thank you @ahrorbeksoft that would be perfect