docs(plans): add playful visual feedback milestone

docs/UI_STYLE.md

@@ -44,8 +44,9 @@ marker.
 
 The gameplay icon family is locally authored SVG artwork derived from the
 approved running-player, key, arched-exit, crystal, opened-exit, and spike
-reference silhouettes. The spike icon communicates only blocked movement or a
-wall collision; it never represents a trap or a new gameplay mechanic.
+reference silhouettes. The spike icon remains a catalog asset only; blocked
+movement uses the maze feedback defined below and never represents a trap or a
+new gameplay mechanic.
 
 WCAG AA contrast certification and dedicated color-vision-deficiency palettes
 are not MVP requirements.
@@ -102,8 +103,10 @@ are not MVP requirements.
 - Connection details and the Wi-Fi settings link belong in a secondary panel,
   not in the persistent status row.
 - Countdown, pause, and result states appear as modal overlays above the map.
-- Errors and rejected actions appear as contextual tooltips or notices near
-  the relevant control or status area.
+- Textual system notices use one live message rail above the top bar and player
+  status area. It shows one message at a time: connection loss has highest
+  priority and persists until recovery; all other messages replace lower
+  priority content, deduplicate by event, and dismiss after 2.6 seconds.
 - The lobby uses separate blocks for players, observers, and match actions.
 - Network provisioning uses the same colors, type, controls, and humor as the
   game application.
@@ -121,8 +124,12 @@ are not MVP requirements.
 - Player zoom and pan controls are not part of the MVP.
 - Use different colors plus labels, outlines, shapes, or icons to distinguish
   player ownership and object types.
-- Give immediate visual feedback when movement is rejected by a wall without
-  revealing hidden state.
+- A server `blocked` rejection shakes the visible maze opposite the attempted
+  cardinal movement for at most 340 ms, without text or spike notice. A
+  `rate_limited` rejection darkens and blurs only the maze for at most 520 ms,
+  also without text. Repeated feedback restarts one bounded effect of each type.
+- Reduced-motion mode replaces the blocked shake with one static directional
+  border cue; rate-limit feedback remains immediate and non-animated.
 
 ## 8. Responsive behavior