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/components/TurnSummary.svelte

@@ -31,14 +31,14 @@
 				</div>
 			{/each}
 		</dl>
-		{#if summary.events?.length}
+		{#if summary.events.length}
 			<ul class="events">
 				{#each summary.events as e, i (i)}
 					<li>{e}</li>
 				{/each}
 			</ul>
 		{/if}
-		{#if duel.showLessons && summary.lessons?.length}
+		{#if duel.showLessons && summary.lessons.length}
 			<ul class="lessons">
 				{#each summary.lessons as l, i (i)}
 					<li>{l}</li>
@@ -58,7 +58,7 @@
 		font-size: 0.9rem;
 	}
 
-	/* On a phone, leave the last two ledger rows in view above the result. */
+	/* On a phone, leave the last two ledger rows in view above the result. Must match COMPACT_QUERY in duel.svelte.ts. */
 	@media (max-width: 860px) {
 		.result {
 			scroll-margin-top: 9.5rem;