feat(ui): replace gameplay icons with local SVGs

MVP.md

@@ -222,9 +222,11 @@ Browser controls must support:
   `docs/UI_STYLE.md`.
 - All player-facing UI copy, game messages, and browser errors are in Russian.
 - The UI uses a near-black background, purple panels, turquoise interactive
-  accents, blue for Player 1, pink for Player 2, and plant-like green maze
-  walls. Important state is distinguished by icons, labels, outlines, or
-  shapes in addition to color.
+  accents, yellow for Player 1, blue for Player 2, and plant-like green maze
+  walls. Each player's matching key and exit use the same ownership color.
+  Important state is distinguished by icons, labels, outlines, or shapes in
+  addition to color; amber warnings and blue pause states use distinct
+  treatments so they cannot be confused with player identity.
 - The player map consumes all space not required by fixed status and control
   panels. The player view supports a minimum `412 x 916` CSS-pixel viewport
   without page scrolling.