Port Fedify CLI to run natively on Node.js and Bun

[dahlia]

As part of the CLI transition to Optique framework (#374), most of the sub-tasks have been completed or are near completion (#396, #397, #398, #399, #400, #408). However, the CLI currently still only runs natively on Deno. Node.js and Bun users continue to receive a compiled binary produced by deno compile through npm, rather than being able to run the JavaScript source directly in their runtime—which defeats one of the main objectives outlined in the parent issue.

Since Optique was specifically designed with cross-runtime compatibility in mind, we should now implement the necessary changes to make the Fedify CLI run natively on Node.js and Bun. This would involve setting up the appropriate entry points for each runtime, handling runtime-specific APIs where necessary, and ensuring the CLI can be executed directly through node or bun commands without requiring pre-compilation. This aligns with our goal of providing a more natural experience for developers across all major JavaScript runtimes and would complete the cross-runtime transition envisioned for Fedify 2.0.