Reset per-game reveal state on new game so reveal animates over cached content

Starting a new game reuses block ids (1,2,3...). The reveal clock's per-block
start times (activeRevealBlockStarts in the lab) and the renderer's animation/
revealed sets are keyed by block id and were never cleared on a client reset, so
a new game over already-cached content inherited the previous run's start times.
beginPageReveal then computed a huge elapsed and the shader treated the reveal as
already complete — showing everything at once instead of animating.

resetClientPlaybackAndDisplay (run on new game and restore) now emits
story:client-reset; the lab clears activeRevealBlockStarts/pending reveal state,
the texture renderer clears active animations and revealed-block ids, and the
timeline invalidates prepared segments. So each game starts with a clean reveal
clock.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

public/js/book-texture-renderer-module.js

@@ -118,6 +118,7 @@ class BookTextureRendererModule extends BaseModule {
         });
         this.addEventListener(document, 'story:manual-scroll', this.fastForwardAnimations);
         this.addEventListener(document, 'story:history-restoring', this.stopAnimations);
+        this.addEventListener(document, 'story:client-reset', this.stopAnimations);
         this.currentSpread = this.pagination?.getCurrentSpread?.() || { index: 0, left: [], right: [], pageMeta: { left: null, right: null } };
         this.drawSpread(this.currentSpread);
         this.reportProgress(100, 'Book texture renderer ready');
@@ -1028,6 +1029,7 @@ class BookTextureRendererModule extends BaseModule {
 
     stopAnimations() {
         this.activeAnimations.clear();
+        this.revealedBlockIds.clear();
         this.drawSpread(this.currentSpread || this.pagination?.getCurrentSpread?.());
     }