[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/nfpm/scripts/postinstall.sh

@@ -0,0 +1,21 @@
+#!/bin/sh
+
+# Update desktop database for .desktop file changes
+# This makes the application appear in application menus and registers its capabilities.
+if command -v update-desktop-database >/dev/null 2>&1; then
+  echo "Updating desktop database..."
+  update-desktop-database -q /usr/share/applications
+else
+  echo "Warning: update-desktop-database command not found. Desktop file may not be immediately recognized." >&2
+fi
+
+# Update MIME database for custom URL schemes (x-scheme-handler)
+# This ensures the system knows how to handle your custom protocols.
+if command -v update-mime-database >/dev/null 2>&1; then
+  echo "Updating MIME database..."
+  update-mime-database -n /usr/share/mime
+else
+  echo "Warning: update-mime-database command not found. Custom URL schemes may not be immediately recognized." >&2
+fi
+
+exit 0

client/ui-wails/build/linux/nfpm/scripts/postremove.sh

@@ -0,0 +1 @@
+#!/bin/bash

client/ui-wails/build/linux/nfpm/scripts/preinstall.sh

@@ -0,0 +1 @@
+#!/bin/bash

client/ui-wails/build/linux/nfpm/scripts/preremove.sh

@@ -0,0 +1 @@
+#!/bin/bash