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

.github/workflows/ci.yml

@@ -0,0 +1,52 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+
+jobs:
+  frontend:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: pnpm/action-setup@v4
+        with:
+          version: 10
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 20
+          cache: pnpm
+      - run: pnpm install --frozen-lockfile
+      - run: pnpm typecheck
+
+  backend:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install system deps
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y \
+            libwebkit2gtk-4.1-dev \
+            libjavascriptcoregtk-4.1-dev \
+            libsoup-3.0-dev \
+            libayatana-appindicator3-dev \
+            librsvg2-dev \
+            libssl-dev \
+            libgtk-3-dev \
+            libxdo-dev \
+            pkg-config \
+            build-essential
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          components: rustfmt, clippy
+      - uses: Swatinem/rust-cache@v2
+        with:
+          workspaces: src-tauri
+      - run: cargo fmt --all -- --check
+        working-directory: src-tauri
+      - run: cargo clippy --all-targets --locked -- -D warnings
+        working-directory: src-tauri
+      - run: cargo test --locked
+        working-directory: src-tauri