Table options: the host's choices when opening a table, declared by the game, recorded on the room line

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Jm2auWk6RP71CjaAb4FMoG

CONVENTIONS.md

@@ -64,6 +64,11 @@ README.
   where the keeper roosts. It lives in the about panel; the colophons, the
   rules page and the guide each carry a one-line mail link.
 
+- **Table options** are the host's choices when opening a table (a
+  variant, a side, a length): the game declares them in `GameSpec.options`,
+  the hall renders them as selects, the room line records them, and
+  `create` receives them. A game with one way to play declares none.
+
 ## The engine
 
 - Pure and deterministic: `create(names, seed, rules)` and