Rate-limit reset banking; developer mode for browser

Several Codex updates including: rate-limit reset banking for eligible Plus and Pro users with one free reset at launch and referral invitation capability; Developer mode for Browser use in Chrome and in-app browser providing controlled Chrome DevTools Protocol access for profiling JavaScript, inspecting console output and network traffic, and diagnosing browser issues (off by default); /init command for generating AGENTS.md project-instructions scaffold; customizable macOS Dock icons; Unread chats section in command menu; and clearer usage-limit errors with plan and workspace guidance.