Fix file changes refresh after session ends

[zzj3720]

Summary

• Treat terminal assistant phases (completed, failed, cancelled) as non-streaming in the embedded chat bridge
• Allows the existing session-end workspaceState refresh / idle fallback polling to update File Changes without switching conversations
• Adds coverage for terminal local assistant phases

Tests

• cd web && yarn test tests/embedded/use-swift-bridge.test.ts
• cd web && yarn typecheck
• cd web && yarn lint
• Remote mini-machine web embedded build passed during setup; full macOS app build was blocked by missing generated sandbox-vm runtime artifacts (SandboxVM.xcframework initially, then kernel.bin / rootfs) on the fresh machine.

Manual validation

• Verified manually by inspecting the session-end refresh path: Swift already calls refreshWorkspaceState() on session finish, and this fix makes the web side leave streaming state on terminal phases so the existing idle polling path can pull refreshed File Changes.
• Full GUI smoke is blocked on the fresh mini-machine until sandbox-vm artifacts are generated.