Credibility pass: one conflict check, one hostile list, one set of chrome

Duplicated logic and styling that had drifted apart is unified: the
gesture-sharing check, the hostile spell list, the enchanted test, the
plan limits, and the shared button, link, field and disabled styles.
Dead plumbing is gone: the always-true implemented flag, the unread
cast length, an unreachable guard, an impossible time-stop condition,
the unused sequence formatter and utility class, the template
placeholder. The counter-spell tests now put a counter-spell in front
of a spell, the test helpers live in one file, and the resolver's
sections are numbered in order. The deploy script's cache headers now
do what its comment says, and the README describes the screen rather
than listing features in the order they arrived.

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

src/lib/game/gestures.ts

@@ -108,19 +108,16 @@ export function usedCells(completion: Completion, hand: Hand, turnCount: number)
 	return cells;
 }
 
+export function cellsOverlap(a: Set<string>, b: Set<string>): boolean {
+	for (const cell of b) if (a.has(cell)) return true;
+	return false;
+}
+
 /** No gesture may complete more than one spell. */
 export function castsConflict(
 	a: { completion: Completion; hand: Hand },
 	b: { completion: Completion; hand: Hand },
 	turnCount: number
 ): boolean {
-	const cellsA = usedCells(a.completion, a.hand, turnCount);
-	for (const cell of usedCells(b.completion, b.hand, turnCount)) {
-		if (cellsA.has(cell)) return true;
-	}
-	return false;
-}
-
-export function formatSequence(spell: Spell, seqIndex = 0): string {
-	return spell.sequences[seqIndex];
+	return cellsOverlap(usedCells(a.completion, a.hand, turnCount), usedCells(b.completion, b.hand, turnCount));
 }