A duel server: rooms, seat tokens, ledgers, and resolution when all have moved

Plain HTTP for actions and a websocket that only says "fetch again". A
room is its append-only ledger replayed from the top; the engine is
deterministic given the seed and the recorded inputs. Each seat sees a
view filtered to what the rules let it know. Bot seats are filled at
resolution time.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

src/lib/game/view.ts

@@ -0,0 +1,16 @@
+// What one wizard is allowed to know. Gestures made while they were blind, or
+// while the other wizard was invisible, are unknown to them; the log lines that
+// describe those gestures are withheld too. Spells cast are always visible, as
+// the rules say.
+
+import { visibleHistory, type GameState, type WizardId } from './state';
+
+export function viewFor(state: GameState, viewer: WizardId): GameState {
+	const view = structuredClone(state);
+	for (const id of view.seats) {
+		if (id === viewer) continue;
+		view.wizards[id].history = visibleHistory(state, viewer, id);
+	}
+	view.log = view.log.filter((l) => !l.hiddenFrom?.includes(viewer));
+	return view;
+}