#974 feat(projects): set and remove a project's logo

Why

basecamp/bc3#14174 lets API clients set and remove a project's logo, the image beside its name, and basecamp-sdk wraps it as of v0.30.0. The CLI has had no way to do either, which is what basecamp/basecamp-sdk#977 asks for.

What changed

• basecamp projects logo set <file> uploads or replaces the logo. It takes PNG, JPEG, GIF, WebP, AVIF, HEIF or HEIC files up to 5 MB, and refuses any other type before uploading. basecamp projects logo remove removes it, and succeeds when there's no logo.
• projects show returns logo in JSON, and the detail view says whether one is set.
• The file check and project read-back that wallpaper used are now shared by both images.

Scope

• This is stacked on #973, which moves the SDK to v0.31.0. Merge it after #973.
• There's no download command, because the SDK doesn't wrap the logo endpoint's redirect. Wallpaper has none either.

Verification

• bin/ci passes.
• Against a local bc3 server with the logo API, I set a logo from a real PNG and checked that the stored image's bytes match the file. Then I removed it, and the project read back with no logo. SVG, text and oversized files were refused before anything was sent.
• An independent GPT-6.1-sol review found nothing to fix.

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Summary by cubic

Adds projects logo set and logo remove so the CLI can set and remove a project's logo, which previously was only possible through the API.

• projects logo set <file> uploads or replaces the logo; accepts PNG, JPEG, GIF, WebP, AVIF, HEIF, or HEIC up to 5 MB and rejects other types before uploading.
• projects logo remove clears the logo and succeeds when the project has none.
• projects show now returns logo in JSON and the detail view reports whether a logo is set.
• The wallpaper file validation and project read-back helpers are now shared by both image types.
• Merges in the latest card-moves-cross-project base branch.
• Addresses basecamp/basecamp-sdk#977, stacked on the SDK v0.31.0 bump in #973.