Curl install script: detect platform, verify checksums, install ship to PATH

[maxBRT]

Parent

#30 Spec: Cross-platform install and self-update via GitHub Releases

What to build

A new user without Go can install Ship with a single curl-piped shell script that detects OS and architecture, downloads the matching asset from the latest GitHub Release, verifies it against published checksums, and installs ship into a conventional user-writable bin directory (such as ~/.local/bin) or a writable system bin when appropriate. Clear errors for unsupported platforms and for install dirs missing from PATH. Windows gets release assets from the same pipeline; the script itself may remain Unix-shell-first. Asset naming and checksum conventions match GoReleaser defaults used by the release pipeline.

Acceptance criteria

• One-liner curl install downloads the correct asset for linux/darwin × amd64/arm64
• Downloaded archive is verified against the published checksums file before install
• Install defaults to a user-writable bin (e.g. ~/.local/bin) without requiring sudo; system bin is available when writable
• Unsupported platform produces a clear error (not a cryptic download failure)
• If the chosen install dir is not on PATH, the script says so clearly
• Downloads use HTTPS to the project’s GitHub Releases
• Asset / checksum naming aligns with the GoReleaser release artifacts from Release pipeline: GoReleaser publishes multi-platform binaries with embedded version #59
• Windows users can obtain matching release assets directly even if the script is Unix-first

Blocked by

• Release pipeline: GoReleaser publishes multi-platform binaries with embedded version #59 Release pipeline: GoReleaser publishes multi-platform binaries with embedded version