P0: scaffold Vite + Vue 3 + Tauri v2

- pnpm + TS + Tailwind 3 + Pinia + Vue Router with hash history
- 6 placeholder views (Status, Peers, Routes, Messages, Topics, Settings)
  rendered via lucide-icon sidebar in App.vue
- Tauri v2: shell, store, log, dialog plugins; bundle targets deb +
  appimage; sidecar wired via externalBin = binaries/mycelium
- scripts/fetch-mycelium.sh pins v0.6.1, maps musl asset onto
  gnu target triple expected by Tauri bundler
- CI: pnpm typecheck + cargo fmt/clippy/test

src/lib/utils.ts

@@ -0,0 +1,23 @@
+import { clsx, type ClassValue } from "clsx";
+import { twMerge } from "tailwind-merge";
+
+export function cn(...inputs: ClassValue[]) {
+  return twMerge(clsx(inputs));
+}
+
+export function formatBytes(bytes: number): string {
+  if (bytes === 0) return "0 B";
+  const k = 1024;
+  const sizes = ["B", "KiB", "MiB", "GiB", "TiB"];
+  const i = Math.floor(Math.log(bytes) / Math.log(k));
+  return `${(bytes / Math.pow(k, i)).toFixed(i === 0 ? 0 : 2)} ${sizes[i]}`;
+}
+
+export function formatRate(bytesPerSec: number): string {
+  return `${formatBytes(bytesPerSec)}/s`;
+}
+
+export function shortenIpv6(addr: string): string {
+  if (addr.length <= 24) return addr;
+  return `${addr.slice(0, 10)}…${addr.slice(-8)}`;
+}