Remove the CI workflow: no Actions runners on the Gitea server

A push that started .github/workflows/ci.yml crashed the server (Adrian,
2026-10-30). The smoke test, self-tests and quick check run locally.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/checklists/phase-0.md

@@ -5,7 +5,7 @@ The agent could not run these: they need the game client, or accepting the Minec
 ## Server (closes the "CI boots the server cleanly" check)
 
 - [x] `python3 tools/smoke_test.py --accept-eula` passed on 2026-10-28 (EULA accepted by Adrian). Server started in 20 s, all 6 RCON checks passed (companion live, 1,025 species, core data pack enabled), no ERROR lines in the log. The 9 WARN lines are expected: offline mode set by the test, Cobblemon's optional Adorn mixin, and a KubeJS client-only plugin.
-- [ ] If the repo goes to GitHub and you accept the EULA for CI too, set the repository variable `MINECRAFT_EULA_ACCEPTED=true`.
+- [x] No CI (Adrian, 2026-10-30: no runners on the Gitea server); the smoke test runs locally.
 
 ## Prism instance "Cobblemon Survival Pack (dev)"