feat: support installing the latest beta release via version: beta

[avallete]

What kind of change does this PR introduce?

The latest channel resolves through the GitHub /releases/latest endpoint, which never returns prereleases, so there was no way to track the CLI beta channel — any other value was treated as an exact version.

Add a beta channel that lists releases and installs the most recent beta prerelease. This lets consumers surface (and fix) breakages early.

[jgoux]

Findings

• P2: src/main.ts fetches only the default first page of GitHub releases when resolving version: beta, despite the comment saying “list all releases.” If the latest beta falls off page 1, version: beta will fail with “no beta release found” even though a beta exists. I’d add per_page=100 at minimum, and ideally follow pagination until a beta is found or the release list is exhausted.
  

  setup-cli/src/main.ts

  Line 212 in 3dacd93

  const response = await fetch(GITHUB_RELEASES_LIST_API, { headers: buildGithubHeaders() });

• P3: action.yml still says github-token is used to resolve only the latest release. README was updated to say latest/beta, so the action metadata should match.
  

  setup-cli/action.yml

  Lines 8 to 9 in 3dacd93

  	github-token:
  	description: GitHub token used to resolve the latest Supabase CLI release without hitting unauthenticated API limits.

Test Gap

The mocked unit coverage is good, but no workflow/e2e path exercises version: beta against the live release API and real archive download. Current matrices still cover only explicit versions and latest; I’d add a small beta smoke case, probably one OS only to keep runtime sane.

• setup-cli/.github/workflows/ci.yml

  Line 49 in 3dacd93

  version: [1.0.0, latest]

• setup-cli/.github/workflows/e2e.yml

  Line 42 in 3dacd93

  - latest

Verification

I reviewed PR 441 at 3dacd93e8f53a2229ed8c0a31d18cdfedf851fcf against main, checked the live Supabase CLI releases API, confirmed the current latest beta has the expected archive assets, and ran the repo validation successfully after the CI setup step:

bun install --frozen-lockfile && bun run ci

Result: format, lint, and 27 tests passed.