Dashboard: user menu dropdown above the computer/chat launchers

The top-right user menu's dropdown shared zIndex 50 with the claw-view
computer/chat launcher buttons, so paint order hid it behind them. Lift the
menu (nav 210, close-overlay 200) so it sits on top.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

frontend/src/components/dashboard/UserMenu.tsx

@@ -32,8 +32,8 @@ export function UserMenu({ onOpen }: { onOpen: (t: ToolKey) => void }) {
       </button>
       {open ? (
         <>
-          <button type="button" aria-label="Close" onClick={() => setOpen(false)} style={{ position: "fixed", inset: 0, zIndex: 40, background: "transparent", border: 0 }} />
+          <button type="button" aria-label="Close" onClick={() => setOpen(false)} style={{ position: "fixed", inset: 0, zIndex: 200, background: "transparent", border: 0 }} />
-          <nav style={{ position: "absolute", top: "100%", right: 0, marginTop: 8, zIndex: 50, width: 196, display: "flex", flexDirection: "column", gap: 2, borderRadius: 14, background: "#141417", border: "1px solid rgba(255,255,255,.1)", padding: 8, boxShadow: "0 18px 50px rgba(0,0,0,.55)" }}>
+          <nav style={{ position: "absolute", top: "100%", right: 0, marginTop: 8, zIndex: 210, width: 196, display: "flex", flexDirection: "column", gap: 2, borderRadius: 14, background: "#141417", border: "1px solid rgba(255,255,255,.1)", padding: 8, boxShadow: "0 18px 50px rgba(0,0,0,.55)" }}>
             <div style={{ fontFamily: mono, fontSize: 9, letterSpacing: ".12em", color: "#5a5a62", padding: "4px 10px 6px" }}>TOOLS</div>
             {ITEMS.map((it) => (
               <button