feat(container.scss): add container styles for fixed position and scrolling behavior

feat(container.ts): create container module to handle scrollable behavior and add/remove disableScroll class

fix(customCursor.ts): update append target for cursor element to use container instead of main

fix(stage.ts): update append target for stage element to use container instead of main

fix(stageNav.ts): update append target for navOverlay element to use container instead of main

feat(main.ts): initialize container module and conditionally initialize stage and stageNav modules based on device type

fix(nav.ts): update references to state module functions to use state.get() instead of getState()

assets/scss/_partial/_container.scss

@@ -0,0 +1,19 @@
+.container {
+  position: fixed;
+  top: 0;
+  z-index: 0;
+
+  width: 100vw;
+  height: var(--window-height);
+
+  overflow-y: scroll;
+  overflow-x: hidden;
+  background: white;
+
+  overscroll-behavior: none;
+  -webkit-overflow-scrolling: none;
+}
+
+.disableScroll {
+  pointer-events: none;
+}