fix: TokenPocket mobile deep-link login, desktop empty-state, toast above modal

- Mobile TokenPocket now opens the tpoutside:// sign deep link and returns to
  the original browser to finish login (no wallet in-app browser); desktop
  keeps the QR. Fixes mobile login + logout being trapped in TP's browser.
- Desktop without an injected wallet shows a clear message instead of a dead
  button; TokenPocket login card is always available as a working path.
- Raise toast z-index above the login modal so feedback is visible.
- Add native TokenPocket-login strings across 7 locales.
- Document that the live backend lacks favorites + TokenPocket routes (404),
  the real blocker for those features in production.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/components/Toast.tsx

@@ -61,7 +61,7 @@ export function ToastProvider({ children }: { children: ReactNode }) {
     <ToastContext.Provider value={value}>
       {children}
       <div
-        className="pointer-events-none fixed inset-x-0 bottom-[92px] z-[100] flex flex-col items-center gap-2 px-4 md:bottom-6"
+        className="pointer-events-none fixed inset-x-0 bottom-[92px] z-[200] flex flex-col items-center gap-2 px-4 md:bottom-6"
         aria-live="polite"
         aria-atomic="true"
       >