add: settings menu + menu store

src/index.css

@@ -397,6 +397,153 @@ canvas {
   letter-spacing: 0.03em;
 }
 
+/* In-game settings menu */
+.game-settings-menu {
+  position: fixed;
+  inset: 0;
+  z-index: 40;
+  display: grid;
+  place-items: center;
+  padding: 20px;
+  background: rgba(0, 0, 0, 0.6);
+  color: #ffffff;
+  pointer-events: auto;
+  backdrop-filter: blur(10px);
+}
+
+.game-settings-menu__panel {
+  width: min(460px, 100%);
+  max-height: calc(100vh - 40px);
+  overflow-y: auto;
+  padding: 18px;
+  border: 1px solid rgba(255, 255, 255, 0.12);
+  border-radius: 24px;
+  background: rgba(8, 8, 8, 0.94);
+  box-shadow: 0 28px 90px rgba(0, 0, 0, 0.55);
+}
+
+.game-settings-menu__header {
+  display: flex;
+  align-items: flex-start;
+  justify-content: space-between;
+  gap: 16px;
+  padding: 4px 4px 16px;
+}
+
+.game-settings-menu__header span {
+  color: #8f8f8f;
+  font-size: 0.7rem;
+  font-weight: 700;
+  letter-spacing: 0.16em;
+  text-transform: uppercase;
+}
+
+.game-settings-menu__header h2 {
+  margin: 0.25rem 0 0;
+  font-size: 1.8rem;
+  letter-spacing: -0.06em;
+}
+
+.game-settings-menu__close {
+  display: grid;
+  place-items: center;
+  width: 40px;
+  height: 40px;
+  border: 1px solid rgba(255, 255, 255, 0.14);
+  border-radius: 999px;
+  background: #111111;
+  color: #ffffff;
+  cursor: pointer;
+}
+
+.game-settings-menu__section {
+  display: grid;
+  gap: 12px;
+  padding: 16px 4px;
+  border-top: 1px solid rgba(255, 255, 255, 0.1);
+}
+
+.game-settings-menu__section h3 {
+  margin: 0;
+  color: #d7d7d7;
+  font-size: 0.78rem;
+  font-weight: 700;
+  letter-spacing: 0.12em;
+  text-transform: uppercase;
+}
+
+.game-settings-menu__slider {
+  display: grid;
+  gap: 8px;
+}
+
+.game-settings-menu__slider span,
+.game-settings-menu__checkbox {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 12px;
+  color: #f2f2f2;
+  font-size: 0.9rem;
+  font-weight: 650;
+}
+
+.game-settings-menu__slider strong {
+  color: #8f8f8f;
+  font-size: 0.78rem;
+}
+
+.game-settings-menu__slider input[type="range"] {
+  width: 100%;
+  accent-color: #ffffff;
+}
+
+.game-settings-menu__checkbox {
+  justify-content: flex-start;
+  cursor: pointer;
+}
+
+.game-settings-menu__checkbox input {
+  width: 18px;
+  height: 18px;
+  accent-color: #ffffff;
+}
+
+.game-settings-menu__choice-group {
+  display: grid;
+  grid-template-columns: repeat(2, 1fr);
+  gap: 8px;
+}
+
+.game-settings-menu__choice-group--stacked {
+  grid-template-columns: 1fr;
+}
+
+.game-settings-menu__choice-group button,
+.game-settings-menu__quit {
+  width: 100%;
+  padding: 11px 12px;
+  border: 1px solid #242424;
+  border-radius: 14px;
+  background: #101010;
+  color: #f2f2f2;
+  cursor: pointer;
+  font-size: 0.88rem;
+  font-weight: 680;
+}
+
+.game-settings-menu__choice-group button.active {
+  border-color: #ffffff;
+  background: #ffffff;
+  color: #050505;
+}
+
+.game-settings-menu__quit {
+  margin-top: 8px;
+  border-color: rgba(248, 113, 113, 0.35);
+  color: #fecaca;
+}
+
 /* Debug overlay panels */
 .debug-overlay-layout {
   position: fixed;