fix(builder): keep every game's name and code out of the builder

The builder must be game-agnostic, but its prompts named games: AUTHORING.md
(the model's rules) used three games as examples, the research prompt listed
two games' editions, the schema described containerUser by one game's image,
and every draft prompt included two real templates from the repo, so the
model saw, and could copy, other games' commands and options.

- AUTHORING.md, the research prompt and the schema describe the rules without
  naming a game.
- The draft prompt's format example is now one invented server (no real
  command, options, ports or app id), checked by
  TestExampleTemplateFollowsTheRules against validation and the draft checks.
- Comments, help texts, BUILDER.md and test fixtures use invented names and
  values.
- TestBuilderIsGameAgnostic reads every game's name and id from games/ and
  fails if any appears in the builder's code, tests, rules, schemas or docs.

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

schema/game.schema.json

@@ -17,7 +17,7 @@
 
     "defaultDockerImage": { "description": "Image the game server runs in.", "type": "string", "minLength": 1 },
     "containerUser": {
-      "description": "uid:gid the server runs as, for images built around their own user (ARK's needs 25000:25000). Defaults to 1000:1000; root is never allowed.",
+      "description": "uid:gid the server runs as, for images built around their own user, as inspect-image reports it. Defaults to 1000:1000; root is never allowed.",
       "type": ["string", "null"],
       "pattern": "^[1-9][0-9]{0,8}:[1-9][0-9]{0,8}$"
     },