feat(chat): add queued composer turns

[coder-hhx]

Summary

• add queued composer turns to the desktop GUI, including add-to-queue, interrupt-and-send, run-now, edit, reorder, and delete controls
• align Gateway Web composer styling and queued-turn UI with the GUI
• keep queued message previews single-line with compact clock icons and add queue i18n strings

Tests

• node --test test/chat/chat-turn-queue.test.mjs
• node --test test/webui/chat-turn-queue.test.mjs
• pnpm exec tsc --noEmit in crates/agent-gui
• pnpm exec tsc --noEmit in crates/agent-gateway/web
• pnpm run build in crates/agent-gateway/web