[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/build/linux/appimage/build.sh

@@ -0,0 +1,35 @@
+#!/usr/bin/env bash
+# Copyright (c) 2018-Present Lea Anthony
+# SPDX-License-Identifier: MIT
+
+# Fail script on any error
+set -euxo pipefail
+
+# Define variables
+APP_DIR="${APP_NAME}.AppDir"
+
+# Create AppDir structure
+mkdir -p "${APP_DIR}/usr/bin"
+cp -r "${APP_BINARY}" "${APP_DIR}/usr/bin/"
+cp "${ICON_PATH}" "${APP_DIR}/"
+cp "${DESKTOP_FILE}" "${APP_DIR}/"
+
+if [[ $(uname -m) == *x86_64* ]]; then
+    # Download linuxdeploy and make it executable
+    wget -q -4 -N https://github.com/linuxdeploy/linuxdeploy/releases/download/continuous/linuxdeploy-x86_64.AppImage
+    chmod +x linuxdeploy-x86_64.AppImage
+
+    # Run linuxdeploy to bundle the application
+    ./linuxdeploy-x86_64.AppImage --appdir "${APP_DIR}" --output appimage
+else
+    # Download linuxdeploy and make it executable (arm64)
+    wget -q -4 -N https://github.com/linuxdeploy/linuxdeploy/releases/download/continuous/linuxdeploy-aarch64.AppImage
+    chmod +x linuxdeploy-aarch64.AppImage
+
+    # Run linuxdeploy to bundle the application (arm64)
+    ./linuxdeploy-aarch64.AppImage --appdir "${APP_DIR}" --output appimage
+fi
+
+# Rename the generated AppImage
+mv "${APP_NAME}*.AppImage" "${APP_NAME}.AppImage"
+