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>

AUTHORING.md

@@ -47,24 +47,25 @@ Know this before writing anything:
 
 ### The container user
 - Run `gbrgames inspect-image -game <id>`. If the image is built around its own user (it declares
-  `USER`, or locks a home folder to a uid other than 1000), set `containerUser` to that `uid:gid`.
-  Example: ARK's image needs `25000:25000`.
+  `USER`, or locks a home folder to a uid other than 1000), set `containerUser` to that `uid:gid`, as
+  the inspector reports it.
 
 ### The startup command
 - Read settings under the names the agent gives them (see above). `${RCON_PORT}` when the setting is
   `RCONPort` silently ignores the owner's value; it arrives as `RCONPORT`.
 - Use `${VAR:-default}` for anything that may be unset.
 - Only use launch options the game's documentation lists, spelled as it spells them. Servers ignore options
-  they don't know, so an invented one (`-maxplayers` for Valheim) boots fine and its setting does nothing.
+  they don't know, so an invented one boots fine and its setting does nothing.
 - Quote text settings where they're used: `-name "${SERVER_NAME}"`. `ARGS="-name ${SERVER_NAME}"; ./server $ARGS`
   splits "GBRHosting - My Server" into words; build optional arguments in a bash array instead
   (`args=(-name "$SERVER_NAME"); [ -n "$PASSWORD" ] && args+=(-password "$PASSWORD"); ./server "${args[@]}"`).
 - If the image installs the game itself on start, make sure a failed install is retried rather than
-  starting a server that isn't there (see ARK's template).
+  starting a server that isn't there: log in to SteamCMD once (`+login anonymous +quit`) before the
+  install, and retry the install a few times until the server's executable exists.
 
 ### Memory
 - `requiredMemoryMb` is the container's hard limit. A JVM or engine heap must stay about **1 GB below**
-  it: Minecraft's `MEMORY` is `3G` for `4096` MB. A heap equal to the limit is killed on start.
+  it: a `3G` heap for `4096` MB. A heap equal to the limit is killed on start.
 
 ### Settings (`defaultConfig` and `configSchema`)
 - Take keys and default values from what the server really writes: run