Let t3 install and update from another repository's GitHub Releases (T3CODE_RELEASE_REPOSITORY)

[immakermatty]

Problem

t3 installs and updates itself from GitHub Releases. T3CODE_RELEASE_BASE_URL already lets you move the downloads, but the release index is fixed to pingdotgg/t3code (packages/shared/src/cliRelease.ts, scripts/install.sh, scripts/install.ps1).

So a build published from another repository, with the same archive names and SHA256SUMS, can't use t3 update without an exact version, or the install script without T3CODE_VERSION. Both pick "newest" from pingdotgg's index and then try to download that version from the other source.

Our case is a hosted deployment that runs t3 as a background service on many machines. It publishes its own builds, upstream plus a small overlay, from its own repository. Today every update there needs T3CODE_RELEASE_BASE_URL plus an exact version.

Proposal

One optional variable, T3CODE_RELEASE_REPOSITORY=<owner>/<name>, default pingdotgg/t3code. It picks the repository whose releases:

• the release index lists, for t3 update without a version and for the install scripts;
• are downloaded by default, for t3 update, t3 service install and Update server.

What stays as it is:

• T3CODE_RELEASE_BASE_URL still wins for downloads.
• Channels, archive names, checksum verification and the launcher protocol don't change.
• A wrong value fails closed: the index request returns 404, and nothing falls back to another repository.

Out of scope:

• the mobile app's Check for updates, which reads the index on the phone;
• the service unit, which doesn't carry the variable today, the same as T3CODE_RELEASE_BASE_URL.

The change is small:

• cliRelease.ts, cli/update.ts, cloud/pinnedRuntime.ts, cloud/selfUpdate.ts, cloud/bootService.ts;
• the two install scripts;
• a few cases in cliRelease.test.ts.

We have a draft and would only open it with your go-ahead.

Question

Would you accept this as a configuration option of the existing release download settings, once you take enhancement PRs again?