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/window/MainWindow.vue

@@ -0,0 +1,68 @@
+<template>
+	<LayoutCol class="main-window">
+		<LayoutRow :class="'title-bar-row'">
+			<TitleBar :platform="platform" :maximized="maximized" />
+		</LayoutRow>
+		<LayoutRow :class="'workspace-row'">
+			<Workspace />
+		</LayoutRow>
+		<LayoutRow :class="'status-bar-row'">
+			<StatusBar />
+		</LayoutRow>
+	</LayoutCol>
+</template>
+
+<style lang="scss">
+.main-window {
+	height: 100%;
+	overflow: auto;
+}
+
+.title-bar-row {
+	height: 28px;
+	flex: 0 0 auto;
+}
+
+.workspace-row {
+	position: relative;
+	flex: 1 1 100%;
+}
+
+.status-bar-row {
+	flex: 0 0 auto;
+	// Prevents the creation of a scrollbar due to the child's negative margin
+	overflow: hidden;
+}
+</style>
+
+<script lang="ts">
+import { defineComponent } from "vue";
+import TitleBar from "@/components/window/title-bar/TitleBar.vue";
+import StatusBar from "@/components/window/status-bar/StatusBar.vue";
+import LayoutRow from "@/components/layout/LayoutRow.vue";
+import LayoutCol from "@/components/layout/LayoutCol.vue";
+import Workspace from "@/components/workspace/Workspace.vue";
+
+export enum ApplicationPlatform {
+	"Windows" = "Windows",
+	"Mac" = "Mac",
+	"Linux" = "Linux",
+	"Web" = "Web",
+}
+
+export default defineComponent({
+	components: {
+		LayoutRow,
+		LayoutCol,
+		TitleBar,
+		Workspace,
+		StatusBar,
+	},
+	data() {
+		return {
+			platform: ApplicationPlatform.Web,
+			maximized: true,
+		};
+	},
+});
+</script>