feat(agy-status): handle the agy activity status in the sessions tab

[StuBehan]

Summary

Shows Antigravity (agy) busy/idle in the Sessions tab — the agy analog of Claude's per-pid sidecar status. agy has no sidecar, so its live session state is read from the running CLI's local loopback RPC (GetAllCascadeTrajectories) and matched to the session by workspace/cwd. Along the way it generalizes the per-session live-state fields so Claude and agy flow through one path, and factors a shared loopback-RPC client.

Changes

Agy session status (panel/AntigravityLocalServer.swift, SessionStore.swift)

• New AntigravityLocalServer — shared client for the running agy's local Connect-RPC (the Codeium/Windsurf "Cascade" language server; lsof loopback port → HTTP POST, no auth/CSRF, 127.0.0.1 only). liveStatusByWorkspace() calls GetAllCascadeTrajectories, maps CASCADE_RUN_STATUS_{BUSY,RUNNING,CANCELING} → busy / IDLE → idle, keyed by workspace path (latest trajectory per workspace).
• SessionStore.enrichAntigravity — during the 3s poll, when an agy session is present, fetch the workspace statuses and match each agy session by cwd (exact or prefix) → set its live status + last-activity. One RPC per scan, only when agy is running.
• Result: agy sessions get the busy/idle dot (yellow/green), the "busy/idle · Nm ago" status line, and busy-first sort — same as Claude.

Generalized live-state fields (SessionStore, Sessions, CompactView, Panel)

• Session.claudeStatus/claudeName/claudeUpdatedAt → liveStatus/liveTitle/lastActivityAt (agent-agnostic; Claude's sidecar and agy's RPC feed the one path). claudeSessionID unchanged (it's the transcript/event key).

Refactor (AntigravityUsage.swift)

• AntigravityUsageProbe now uses the shared AntigravityLocalServer.call(...) for GetUserStatus, dropping ~64 lines of duplicated port-discovery + HTTP plumbing.

build.sh — new file added to the swiftc source list.

Testing

• swift build → clean; ./build.sh → app builds.
• liveStatusByWorkspace() validated against the live agy 1.0.6 RPC: /Users/stubehan/stackone → idle, correct last-activity time (matches raw GetAllCascadeTrajectories).
• Not exercisable in CI (panel + live agy). Manual check: with an agy session running, its Sessions-tab dot is yellow while it works and green when idle, sorted busy-first; quitting agy leaves the row without live status (it's a live RPC, not persisted).

Related issues

agy local-RPC surface per steipete/CodexBar#1178. Builds on the usage panel (#78) — the shared client is introduced here and the usage probe refactored onto it.