Run the terminal gate in CI, so a core bump can prove itself #164

Owner, 2026-09-19: 'we need automated tests to confirm it never conflicts. that's important. if we can do that in a good way we could auto bump the release too, and users of the app can get an update available banner.' Today npm run e2e:terminal (the required gate for any prism-term-core pin bump) runs only on the owner's machine, which is the one reason a bump PR cannot merge by itself. Spike first: does the gate run green and STABLY on a GitHub Windows runner (real Electron window, real pwsh via node-pty, the fake-microphone dictation scenario with the Tiny model)? If yes: make it a required check on bump PRs, let those auto-merge (with a patch version bump so release.yml publishes a NEW release and the update chip fires), and write down what stays manual.