[Feature]: Allow update to @latest release

[rcollette]

Problem Statement

Currently I have to run a small script just to be able to determine what the current release is. Omitting the version number results in .dev builds being installed.

LATEST_TAG="$(
  python3 - <<'PY'
import json
import urllib.request

with urllib.request.urlopen('https://api.github.com/repos/github/spec-kit/releases/latest') as response:
	print(json.load(response)['tag_name'])
PY
)"

uv tool install specify-cli --force --from "git+https://github.com/github/spec-kit.git@${LATEST_TAG}"
specify init --here --force --ai copilot

Proposed Solution

Initial and subsequent installs should only use released versions, automatically. Similar to the copilot cli, the specify cli should indicate when there is an upgrade available and should be capable of self updating, OR there should be a way to refer to an @latest tag only.

Alternatives Considered

No response

Component

Specify CLI (initialization, commands)

AI Agent (if applicable)

None

Use Cases

1. When upgrading spec kit

Acceptance Criteria

No response

Additional Context

No response