Rules: add card diagrams to the Example of Play (v3)

The Cheesy Heist walkthrough was a wall of text. Add a card-state diagram at
each step (after the draw, and after each of the three Challenges) showing both
Obstacle columns as they grow — reusing the same overlapping-column visual as
the in-app obstacle display: original card at the back with a gold ring, plays
stacked in front (green = beat the difficulty, red = didn't), newest in full
view. Self-contained CSS in rules.html; card faces stay light parchment in both
themes. Verified in light/dark and on mobile.

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

frontend/src/lib/changelog.js

@@ -6,10 +6,17 @@
 //   - Add a CHANGELOG entry only when a commit changes something players can
 //     see. Skip refactors, tests, and tooling. Keep wording player-facing.
 
-export const VERSION = 2;
+export const VERSION = 3;
 
 // Newest first. Each entry: { version, date: 'YYYY-MM-DD', changes: [string, ...] }.
 export const CHANGELOG = [
+    {
+        version: 3,
+        date: '2026-06-15',
+        changes: [
+            'The rulebook’s Example of Play now has card diagrams at each step, showing how each Obstacle’s column grows as the scene unfolds.',
+        ],
+    },
     {
         version: 2,
         date: '2026-06-15',