[idea] Implement session restore for Antigravity (agy)

[Naerelyth]

idea / problem

Currently, Herdr's native agent session restore feature supports many popular CLI agents (like Codex, Claude Code, and Pi), but it does not yet support the Antigravity (agy) CLI.

requested change

Please add session tracking for the Antigravity (agy) agent. Herdr should be able to capture the agy session ID upon startup via the integration hooks, save it to the session state, and automatically inject the appropriate resume command (agy --conversation <id>) when restoring the pane after a restart.

why you want this

Adding this support will prevent the frustrating loss of agent session when Herdr restarts. It will provide the same seamless, "memory-persistent" developer experience for Antigravity users that is currently enjoyed by users of other supported agents.

[adamkrellenstein]

This is very straightforward to support—agy accepts --conversation <id> to resume existing sessions. Can we turn this to an issue, @ogulcancelik ?

[ogulcancelik]

if you are up for a pr for sure, let me know

[adamkrellenstein]

Yep, definitely!

[ludoo]

This is already implemented in a fork, which I posted about here #1011 in a discussion

https://github.com/ludoo/herdr/tree/feature/antigravity-cli-integration

[ludoo]

(auto-closed) PR #2087 is in, @ogulcancelik can you give it a read? This is the same code I originally proposed in discussion #1011