Restructure project directories (#333)

`/client/web` -> `/frontend`
`/client/cli` -> *delete for now*
`/client/native` -> *delete for now*
`/core/editor` -> `/editor`
`/core/document` -> `/graphene`
`/core/renderer` -> `/charcoal`
`/core/proc-macro` -> `/proc-macros` *(now plural)*

frontend/src/components/widgets/scrollbars/PersistentScrollbar.vue

@@ -0,0 +1,148 @@
+<template>
+	<div class="persistent-scrollbar" :class="direction.toLowerCase()">
+		<button class="arrow decrease"></button>
+		<div class="scroll-track">
+			<div class="scroll-click-area decrease" :style="[trackStart, preThumb, sides]"></div>
+			<div class="scroll-thumb" :style="[thumbStart, thumbEnd, sides]"></div>
+			<div class="scroll-click-area increase" :style="[postThumb, trackEnd, sides]"></div>
+		</div>
+		<button class="arrow increase"></button>
+	</div>
+</template>
+
+<style lang="scss">
+.persistent-scrollbar {
+	display: flex;
+	flex: 1 1 100%;
+
+	.arrow {
+		flex: 0 0 auto;
+		display: block;
+		background: none;
+		outline: none;
+		border: none;
+		border-style: solid;
+		width: 0;
+		height: 0;
+		padding: 0;
+	}
+
+	.scroll-track {
+		flex: 1 1 100%;
+		position: relative;
+
+		.scroll-thumb {
+			position: absolute;
+			border-radius: 4px;
+			background: var(--color-5-dullgray);
+
+			&:hover {
+				background: var(--color-6-lowergray);
+			}
+		}
+
+		.scroll-click-area {
+			position: absolute;
+		}
+	}
+
+	&.vertical {
+		flex-direction: column;
+
+		.arrow.decrease {
+			margin: 4px 3px;
+			border-width: 0 5px 8px 5px;
+			border-color: transparent transparent var(--color-5-dullgray) transparent;
+
+			&:hover {
+				border-color: transparent transparent var(--color-6-lowergray) transparent;
+			}
+		}
+
+		.arrow.increase {
+			margin: 4px 3px;
+			border-width: 8px 5px 0 5px;
+			border-color: var(--color-5-dullgray) transparent transparent transparent;
+
+			&:hover {
+				border-color: var(--color-6-lowergray) transparent transparent transparent;
+			}
+		}
+	}
+
+	&.horizontal {
+		flex-direction: row;
+
+		.arrow.decrease {
+			margin: 3px 4px;
+			border-width: 5px 8px 5px 0;
+			border-color: transparent var(--color-5-dullgray) transparent transparent;
+
+			&:hover {
+				border-color: transparent var(--color-6-lowergray) transparent transparent;
+			}
+		}
+
+		.arrow.increase {
+			margin: 3px 4px;
+			border-width: 5px 0 5px 8px;
+			border-color: transparent transparent transparent var(--color-5-dullgray);
+
+			&:hover {
+				border-color: transparent transparent transparent var(--color-6-lowergray);
+			}
+		}
+	}
+}
+</style>
+
+<script lang="ts">
+import { defineComponent, PropType } from "vue";
+
+export enum ScrollbarDirection {
+	"Horizontal" = "Horizontal",
+	"Vertical" = "Vertical",
+}
+
+export default defineComponent({
+	props: {
+		direction: { type: String as PropType<ScrollbarDirection>, default: ScrollbarDirection.Vertical },
+	},
+	computed: {
+		trackStart(): { left: string } | { top: string } {
+			return this.direction === ScrollbarDirection.Vertical ? { top: "0%" } : { left: "0%" };
+		},
+		preThumb(): { right: string } | { bottom: string } {
+			const start = 25;
+
+			return this.direction === ScrollbarDirection.Vertical ? { bottom: `${100 - start}%` } : { right: `${100 - start}%` };
+		},
+		thumbStart(): { left: string } | { top: string } {
+			const start = 25;
+
+			return this.direction === ScrollbarDirection.Vertical ? { top: `${start}%` } : { left: `${start}%` };
+		},
+		thumbEnd(): { right: string } | { bottom: string } {
+			const end = 25;
+
+			return this.direction === ScrollbarDirection.Vertical ? { bottom: `${end}%` } : { right: `${end}%` };
+		},
+		postThumb(): { left: string } | { top: string } {
+			const end = 25;
+
+			return this.direction === ScrollbarDirection.Vertical ? { top: `${100 - end}%` } : { left: `${100 - end}%` };
+		},
+		trackEnd(): { right: string } | { bottom: string } {
+			return this.direction === ScrollbarDirection.Vertical ? { bottom: "0%" } : { right: "0%" };
+		},
+		sides(): { left: string; right: string } | { top: string; bottom: string } {
+			return this.direction === ScrollbarDirection.Vertical ? { left: "0%", right: "0%" } : { top: "0%", bottom: "0%" };
+		},
+	},
+	data() {
+		return {
+			ScrollbarDirection,
+		};
+	},
+});
+</script>