feat: implement bl space upload-attachment (POST /api/v2/space/attachment)

[23prime]

Type

feat

Summary

Implement bl space upload-attachment <file> command to upload a file as a space attachment and return the attachment ID.

Changes

• Add POST /api/v2/space/attachment support in src/api/space.rs
• Add bl space upload-attachment <file> subcommand in src/cmd/space/upload_attachment.rs
• May require reqwest multipart feature
• Update docs: website/docs/commands.md, website/i18n/ja/...

Notes

Returns an Attachment object containing the attachment ID, which can be referenced when creating issues or wiki pages.