[management,client] 0.75.0 release with new desktop UI (#6473)

- **Wails v3 application** (`client/ui`) with a React + TypeScript + Tailwind frontend replacing the Fyne UI: main connection view, exit-node switcher, networks/peers browser with detail panels, profile management, settings (general, network, SSH, security, troubleshooting, appearance), debug-bundle creation, and a first-run welcome flow.
- **Internationalization**: go-i18n bundle with 9 locales (en, de, es, fr, hu, it, pt, ru, zh-CN) shared between the tray and the frontend.
- **New system tray** implementation with per-platform theme-aware icons, including a native XEmbed host for Linux (`xembed_tray_linux.c`) and a Linux theme watcher.
- **Session handling**: auth session watcher (`client/internal/auth/sessionwatch`), pending login flow, session-expiration dialog and tray notifications, and `netbird login` improvements.
- **Daemon API extensions** (`daemon.proto`): status stream subscription, event stream, networks/exit-node selection endpoints, and richer full status — with probe throttling on the daemon side to protect against UI-driven request storms.
- **UI preferences store** persisted per profile, autostart management via the daemon (single source of truth in HKCU on Windows).
- **Build system**: Taskfile-based builds per platform (macOS, Linux, Windows), Docker cross-compilation images, MSIX/NSIS/nfpm/AppImage packaging, and a new `frontend-ui` CI workflow.

Co-authored-by: Zoltan Papp <zoltan.pmail@gmail.com>
Co-authored-by: Eduard Gert <kontakt@eduardgert.de>
Co-authored-by: braginini <bangvalo@gmail.com>
Co-authored-by: Pascal Fischer <32096965+pascal-fischer@users.noreply.github.com>
Co-authored-by: riccardom <riccardomanfrin@gmail.com>

client/ui/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"
+