feat: 1-to-1 message render + web data-lake backend

frontend/src/app.html

@@ -4,6 +4,16 @@
 		<meta charset="utf-8" />
 		<meta name="viewport" content="width=device-width, initial-scale=1" />
 		<meta name="text-scale" content="scale" />
+		<script>
+			(() => {
+				const stored = localStorage.getItem("bg.theme");
+				const dark =
+					stored === "dark" ||
+					((stored === "system" || stored === null) &&
+						window.matchMedia("(prefers-color-scheme: dark)").matches);
+				if (dark) document.documentElement.classList.add("theme-dark");
+			})();
+		</script>
 		%sveltekit.head%
 	</head>
 	<body data-sveltekit-preload-data="hover">