style(motion): add strict animations and fix layout properties

- Change ReadingProgress and RouteTable to use transform (scaleX/scaleY) instead of width/height
- Convert existing easing functions to 200ms cubic-bezier(.2,0,0,1)
- Document animation purpose with CSS comments
- Add guide panel swap, review desk detail swap, and tally pop animations
- Implement prefers-reduced-motion for all new states

src/components/blocks/ChangeLens.astro

@@ -137,7 +137,8 @@ const isDiff = mode === 'diff';
   .skill-diff {
     border: 1px solid var(--ink);
     color: var(--paper);
-    animation: lens-enter 0.28s ease both;
+    /* purpose: change lens reveal (state change) */
+    animation: lens-enter 200ms cubic-bezier(0.2, 0, 0, 1) both;
   }
 
   .change-lens {

src/components/blocks/VoteWidget.astro

@@ -139,4 +139,27 @@ const share = (count: number) => (total ? Math.round((count / total) * 100) : 0)
       flex-direction: column;
     }
   }
+
+  .vote-buttons button b {
+    display: inline-block;
+  }
+  :global(.is-updating) {
+    /* purpose: vote widget tally update (feedback) */
+    animation: tally-pop 200ms cubic-bezier(0.2, 0, 0, 1) both;
+  }
+  @keyframes tally-pop {
+    from {
+      opacity: 0;
+      transform: translateY(-4px);
+    }
+    to {
+      opacity: 1;
+      transform: translateY(0);
+    }
+  }
+  @media (prefers-reduced-motion: reduce) {
+    :global(.is-updating) {
+      animation: none;
+    }
+  }
 </style>