fix(acp): keep tool cards visible

[wgqqqqq]

Summary

• Attach ACP tool events to the active model round and emit model-round completion events for ACP streams.
• Keep completed tool cards visible when explore grouping is disabled, so ACP sessions do not hide tool cards without a folded summary.

Verification

• cargo check -p bitfun-desktop
• pnpm run type-check:web
• pnpm --dir src/web-ui run test:run src/flow_chat/components/modern/modelRoundItemGrouping.test.ts src/flow_chat/store/modernFlowChatStore.test.ts