[client/ui] Fix tray submenu not updating on KDE/Plasma

The Profiles and Exit Node submenus (and the About version/Update rows)
stopped reflecting changes on KDE/Plasma: after the first profile switch
the menu froze on its initial snapshot, and "Manage Profiles" — plus the
profile rows themselves — stopped responding to clicks entirely.

Root cause (confirmed via dbus-monitor): Plasma's StatusNotifierItem host
caches a submenu's layout the first time it is opened (GetLayout for that
submenu id) and never re-fetches it on a LayoutUpdated(parent=0) signal.
The old submenu.Clear()+Add() repaint allocated fresh monotonic item ids
each time but reused the same submenu container id, so Plasma kept showing
the stale snapshot and, on click, sent the stale ids back — which the
rebuilt itemMap no longer knew, silently no-op'ing the click.

Fix: route every dynamic tray-menu change through a new relayoutMenu that
rebuilds the whole tree (buildMenu + repaint cached state + a single
SetMenu), allocating brand-new submenu container ids. Plasma treats those
as unseen and re-queries them on next open, fixing both the stale paint
and the dead clicks. loadProfiles/refreshExitNodes now cache their rows
and drive relayoutMenu; the update row goes through a new onMenuChange
hook; the daemon-version row relayouts too. relayoutMenu is serialised by
menuMu and the fill*Submenu helpers are pure UI (no fetch, no SetMenu) so
it never recurses. The whole-tree SetMenu also subsumes the prior darwin
detached-NSMenu workaround.

client/ui/CLAUDE.md

@@ -9,6 +9,7 @@ This is the Wails v3 desktop UI for NetBird. Go services live in `services/`; th
 ### Go (top-level package `main`)
 - `main.go` — app entry. Builds the shared gRPC `Conn`, constructs services, registers them with Wails, creates the main webview window, then starts (in order) the Linux SNI watcher → tray → `peers.Watch` → `app.Run`. CLI flags: `--daemon-addr`, `--log-file` (repeatable; first user-provided value drops the seeded `console` default), `--log-level` (`trace|debug|info|warn|error`, default `info`).
 - `tray.go` — `Tray` struct + menu. Subscribes to `EventStatus`, `EventSystem`, `EventUpdateAvailable`, `EventUpdateProgress`. Owns per-status icon/dot, Profiles submenu, Connect/Disconnect swap, About → Update, session-expired toast.
+- **Tray menu updates go through `relayoutMenu` (whole-tree rebuild), never in-place submenu mutation.** Any dynamic menu change — Profiles submenu (`tray_profiles.go loadProfiles` → caches rows under `profilesMu`, then `fillProfileSubmenu`), Exit Node submenu (`tray_exitnodes.go refreshExitNodes` → `fillExitNodeSubmenu`), daemon-version row (`tray_status.go`), and the About → Update row (`tray_update.go applyState` → `onMenuChange` callback) — rebuilds the entire menu via `Tray.relayoutMenu` (`buildMenu()` + repaint cached state + single `t.tray.SetMenu`). Serialised by `menuMu`. **Why:** on KDE/Plasma the StatusNotifierItem host caches a submenu's layout the first time it's opened (`GetLayout` for that submenu id) and never re-fetches it on a `LayoutUpdated(parent=0)` signal — so the old `submenu.Clear()`+`Add()` left both the visible rows AND the click→id mapping frozen on the first snapshot. Because `Clear()`+`Add()` allocates fresh monotonic item ids each time (Wails `menuitem.go`), clicks then sent ids the rebuilt `itemMap` no longer knew, and silently no-op'd ("Manage Profiles" stopped responding after the first switch). `buildMenu()` allocates a brand-new submenu container id each relayout, which Plasma treats as unseen and re-queries on next open — fixing both the stale paint and the dead clicks. Confirmed via `dbus-monitor`: a re-opened submenu issued no `GetLayout` until its container id changed. The whole-tree `SetMenu` also subsumes the older darwin detached-NSMenu workaround. `fill*Submenu` helpers are pure UI (read caches, no daemon fetch, no `SetMenu`) so `relayoutMenu` never recurses back into the fetchers.
 - `tray_linux.go` — `init()` sets `WEBKIT_DISABLE_DMABUF_RENDERER=1` (blank-white window on VMs / minimal WMs) and `WEBKIT_DISABLE_COMPOSITING_MODE=1` (Intel/Mesa SIGSEGV in `g_application_run` via unimplemented DRM-format-modifier paths — DMABUF-disable alone doesn't cover the GL compositor). Both are skipped if the user already set the var. Also `WEBKIT_DISABLE_SANDBOX_THIS_IS_DANGEROUS=1` when unprivileged userns are blocked.
 - `tray_watcher_linux.go`, `xembed_host_linux.go`, `xembed_tray_linux.{c,h}` — in-process SNI watcher + XEmbed bridge for minimal WMs. See `LINUX-TRAY.md`.
 - `signal_unix.go` / `signal_windows.go` — `listenForShowSignal`. Unix uses SIGUSR1; Windows uses a named event `Global\NetBirdQuickActionsTriggerEvent`. Mirrors the legacy Fyne UI's external-trigger contract so the installer / CLI keep working.