[client] Add Wails3 + React desktop UI scaffold

Stage 1 of the client/ui (Fyne) replacement. Adds a new client/ui-wails
module that runs on Linux/macOS/Windows from a single React + Vite +
Tailwind frontend driven by a thin gRPC services layer in Go.

- Single-module integration (no submodule): merge Wails3 into root go.mod
  with build tags !android !ios !freebsd !js so cross-compiles on those
  targets exclude the package automatically.
- Seven gRPC-bound services: Connection, Settings, Networks, Profiles,
  Debug, Update, Peers. Peers bridges Status polling and SubscribeEvents
  to the Wails event bus (netbird:status, netbird:event).
- Tray + window shell mirrors the Fyne menu 1:1 with hide-on-close,
  SIGUSR1 / Windows named-event for external "show window" triggers.
- React pages cover functional parity for Status, Settings (3 tabs),
  Networks (3 tabs), Profiles, Debug, Update, QuickActions, LoginUrl.
- SVG-sourced tray icons (12 source SVGs incl. macOS template variants)
  rasterized to PNG via task common:generate:tray:icons.
- Linux launcher sets WEBKIT_DISABLE_DMABUF_RENDERER=1 in the .desktop
  Exec= line and in task linux:run so the app renders correctly under
  RDP, VirtualBox, KVM, and bare WMs (Fluxbox/dwm) without DRM access.

client/ui-wails/frontend/public/style.css

@@ -0,0 +1,157 @@
+:root {
+    font-family: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", "Roboto",
+    "Oxygen", "Ubuntu", "Cantarell", "Fira Sans", "Droid Sans", "Helvetica Neue",
+    sans-serif;
+    font-size: 16px;
+    line-height: 24px;
+    font-weight: 400;
+    color-scheme: light dark;
+    color: rgba(255, 255, 255, 0.87);
+    background-color: rgba(27, 38, 54, 1);
+    font-synthesis: none;
+    text-rendering: optimizeLegibility;
+    -webkit-font-smoothing: antialiased;
+    -moz-osx-font-smoothing: grayscale;
+    -webkit-text-size-adjust: 100%;
+    user-select: none;
+    -webkit-user-select: none;
+    -moz-user-select: none;
+    -ms-user-select: none;
+}
+
+@font-face {
+    font-family: "Inter";
+    font-style: normal;
+    font-weight: 400;
+    src: local(""),
+    url("./Inter-Medium.ttf") format("truetype");
+}
+
+h3 {
+    font-size: 3em;
+    line-height: 1.1;
+}
+
+a {
+    font-weight: 500;
+    color: #646cff;
+    text-decoration: inherit;
+}
+
+a:hover {
+    color: #535bf2;
+}
+
+button {
+    width: 60px;
+    height: 30px;
+    line-height: 30px;
+    border-radius: 3px;
+    border: none;
+    margin: 0 0 0 20px;
+    padding: 0 8px;
+    cursor: pointer;
+}
+
+.result {
+    height: 20px;
+    line-height: 20px;
+}
+
+body {
+    margin: 0;
+    display: flex;
+    place-items: center;
+    place-content: center;
+    min-width: 320px;
+    min-height: 100vh;
+}
+
+.container {
+    display: flex;
+    flex-direction: column;
+    align-items: center;
+    justify-content: center;
+}
+
+h1 {
+    font-size: 3.2em;
+    line-height: 1.1;
+}
+
+#app {
+    max-width: 1280px;
+    margin: 0 auto;
+    padding: 2rem;
+    text-align: center;
+}
+
+.logo {
+    height: 6em;
+    padding: 1.5em;
+    will-change: filter;
+}
+
+.logo:hover {
+    filter: drop-shadow(0 0 2em #e80000aa);
+}
+
+.logo.react:hover {
+    filter: drop-shadow(0 0 2em #61dafbaa);
+}
+
+.result {
+    height: 20px;
+    line-height: 20px;
+    margin: 1.5rem auto;
+    text-align: center;
+}
+
+.footer {
+    margin-top: 1rem;
+    align-content: center;
+    text-align: center;
+}
+
+@media (prefers-color-scheme: light) {
+    :root {
+        color: #213547;
+        background-color: #ffffff;
+    }
+
+    a:hover {
+        color: #747bff;
+    }
+
+    button {
+        background-color: #f9f9f9;
+    }
+}
+
+
+.input-box .btn:hover {
+    background-image: linear-gradient(to top, #cfd9df 0%, #e2ebf0 100%);
+    color: #333333;
+}
+
+.input-box .input {
+    border: none;
+    border-radius: 3px;
+    outline: none;
+    height: 30px;
+    line-height: 30px;
+    padding: 0 10px;
+    color: black;
+    background-color: rgba(240, 240, 240, 1);
+    -webkit-font-smoothing: antialiased;
+}
+
+.input-box .input:hover {
+    border: none;
+    background-color: rgba(255, 255, 255, 1);
+}
+
+.input-box .input:focus {
+    border: none;
+    background-color: rgba(255, 255, 255, 1);
+}