feat: support image replies in twitter reply

[YoungCan-Wang]

Summary

• add image reply support to opencli twitter reply via --image
• add remote image reply support via --image-url
• keep the existing text-only reply flow intact and cover the new paths with adapter tests

Usage

opencli twitter reply "<tweet-url>" "<reply-text>" --image /abs/path/to/image.png
opencli twitter reply "<tweet-url>" "<reply-text>" --image-url https://example.com/image.png

Validation

• npm run typecheck
• npx vitest run --project adapter src/clis/twitter/reply.test.ts
• npm run build