chore(release): Thunderstore packaging and release automation

[aram-devdocs]

Package both products for Thunderstore (tcli), wire release-please with Conventional-Commit titles, and publish GitHub Release zips. No game IP in any artifact; every job no-ops cleanly when its secret is absent.

Blocked by #5. thunderstore/ manifests + release.yml + package scripts authored; needs the team namespace registered and a first dry-run.

[aram-devdocs]

Handoff: thunderstore/{api,client} manifests + README, package-thunderstore.ps1 (build+stage+manifest-sync+game-IP audit+tcli), release.yml, and Versions.props are all on dev. Remaining (human): (a) add real 256×256 thunderstore/api/icon.png + thunderstore/client/icon.png (tcli build hard-requires them; no placeholder committed); (b) register the Thunderstore namespace (currently the placeholder aram_devdocs) + set the TCLI_AUTH_TOKEN secret; (c) DECIDE: wire release-please vs. ratify the current tag-driven releases (the repo deliberately chose tag-driven); (d) run a first packaging dry-run.