feat(net): parallel Check + timeout counters + GUI tooltips/order

Networking (anti-freeze):
- Add check_transactions_parallel: pressing "Check" now contacts will-executors
  concurrently with a fast-fail timeout (CHECK_TIMEOUT=8, 1 retry) and a global
  deadline (CHECK_GLOBAL_DEADLINE=30), so a single dead server no longer freezes
  the "checking transaction" dialog for ~140s (old default 10s x 10 retries).
- check_transaction now accepts timeout/max_retries/retry_sleep kwargs.
- Rewrite BalWindow.check_transactions_task to use the parallel helper with live
  progress + an elapsed-time counter "Checking transactions: 2/5 (4s / 30s)".

Reliable elapsed-time counters (Xs / DEADLINEs):
- Replace the unreliable raw heartbeat thread (whose pyqtSignal emissions were
  not marshalled and never repainted) with an on_tick callback driven from the
  CALLING thread in push/ping/check parallel helpers.
- Show the maximum wait too (e.g. "3s / 30s") so the user knows when the
  operation will give up, in the wizard Broadcasting, Ping and Check dialogs.
- Expose networking constants (PUSH_*/CHECK_*/DEFAULT_TIMEOUT) as Willexecutors
  class attributes for a single source of truth in the GUI.

GUI:
- Add hover tooltips: Wizard ("Wizard - Build your will"), Delivery time (truck),
  Check Alive (siren), Calendar, Check (refresh).
- Reorder the Will toolbar to: Wizard | Delivery time | Check Alive | Calendar |
  Check; tighten layout margins so it all fits the Will window.

Tests:
- parallel_ping_test.py: add coverage for check_transactions_parallel (parallel
  timing, global deadline, on_tick from the calling thread) and static checks
  that check_transactions_task/loop_push use the parallel helpers + on_tick
  counter with the 'Xs / Ns' format.

Verified: ruff (0 new issues), 182 official tests pass, parallel/smoke/gui_fixes/
windows_overflow/external_zip tests pass.

bal/gui/qt/lists.py

@@ -451,6 +451,8 @@ class PreviewList(MyTreeView, MessageBoxMixin):
                 self.bal_window.bal_plugin.read_file("icons/wizard.png")
             )
         )
+        # Tooltip so the icon is self-explanatory when hovered.
+        wizard.setToolTip(_("Wizard - Build your will"))
         wizard.clicked.connect(self.bal_window.init_wizard)
         # display = QPushButton(_("Display"))
         # display.clicked.connect(self.bal_window.preview_modal_dialog)
@@ -461,13 +463,20 @@ class PreviewList(MyTreeView, MessageBoxMixin):
                 self.bal_window.bal_plugin.read_file("icons/reload.png")
             )
         )
+        # Tooltip so the icon is self-explanatory when hovered.
+        refresh.setToolTip(_("Check"))
         refresh.clicked.connect(self.check)
 
         widget = QWidget(self)
         hlayout = QHBoxLayout(widget)
+        hlayout.setContentsMargins(0, 0, 0, 0)
         self.will_settings_widget = WillSettingsWidget(self.bal_window, self)
-        hlayout.addWidget(self.will_settings_widget)
+        # Toolbar order (left -> right):
+        #   Wizard | Delivery time | Check Alive | Calendar | Check (refresh)
+        # The Wizard button goes first (leftmost); the settings widget already
+        # lays out delivery/check-alive/calendar in that order internally.
         hlayout.addWidget(wizard)
+        hlayout.addWidget(self.will_settings_widget)
         hlayout.addWidget(refresh)
         toolbar.insertWidget(2, widget)