Deploy the Television update channel

Release builds of the Television server poll https://television.run/update-channel.json by default and relay what it says to their clients: an update notice when the announced release is newer than the server, and upgrade instructions for desktop apps too old for their server. Its master copy is specs/arch/updates/update-channel.json in the Television repository, telepath-computer/television. Deploying makes the public file a verbatim copy of the master copy on freshly fetched, merged Television origin/main.

specs/arch/updates/update-channel.md governs the channel: the document's schema, what goes in it, and how it is published. The runbook specs/arch/updates/runbook-channel-deploy.md owns the procedure. It covers announcing a release, which starts with a Television pull request to the master copy and sometimes a required-desktop-version bump, and publishing a master-copy change that has already merged.

The website repository is telepath-computer/television.run, where the channel file is site/public/update-channel.json. The site deploys from its main, so merging a site pull request publishes the channel; leave merging to the human.

The site is a DigitalOcean App Platform static site behind Cloudflare. App Platform fixes Cache-Control: public,max-age=10,s-maxage=86400, so the edge may hold a file for up to a day, and each site deployment invalidates the edge cache. Verify a deploy by fetching the plain https://television.run/update-channel.json, with no query string, and confirming it serves the new master copy, which shows the edge cache was invalidated. Do not verify with a cache-busting query, which does not check the cached response at the plain public URL.

The notice's upgrade prompt normally sends users' agents to https://television.run/install.md, which the deploy-tv-admin-guide skill publishes.