chore: move to public gitea instance and drop project-local gitea MCP

- Remove the project-local gitea MCP (opencode.json) and gitea-mcp-server
  from the dev shell — the gitea MCP is now installed globally and points
  at https://gitea.edley.me
- Update README/project.md links and the flake package homepage to the
  new public instance
- The GITEA_ACCESS_TOKEN for the old homeserver is removed from
  .secrets.env (gitignored); the global token from /run/secrets is used

README.md

@@ -84,8 +84,8 @@ Three distribution formats are provided. Prebuilt artifacts are tracked in
 the repo under `dist/` (click to view on the remote; raw downloads require
 access to the Gitea server):
 
-- [AppImage](http://homeserver:3050/pedley/TeleportFling/src/branch/main/dist/TeleportFling-0.1.0-x86_64.AppImage)
-- [Debian/Ubuntu .deb](http://homeserver:3050/pedley/TeleportFling/src/branch/main/dist/teleportfling_0.1.0_amd64.deb)
+- [AppImage](https://gitea.edley.me/petere/TeleportFling/src/branch/main/dist/TeleportFling-0.1.0-x86_64.AppImage)
+- [Debian/Ubuntu .deb](https://gitea.edley.me/petere/TeleportFling/src/branch/main/dist/teleportfling_0.1.0_amd64.deb)
 
 ### Nix / NixOS