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/widgets.py

@@ -150,6 +150,7 @@ class BalTimeEditWidget(QWidget, _LockTimeEditor):
         + " - y: number of years after currrent day(ex: 1y means one year from today)\n"
     )
     label_text = None
+    tooltip_text = None
     base_field = None
 
     def __init__(self, bal_window, parent, default_locktime=None):
@@ -182,6 +183,10 @@ class BalTimeEditWidget(QWidget, _LockTimeEditor):
         #hbox.addWidget(QLabel(self.label_text))
         help_button=HelpButton(self.help_text)
         help_button.setText(self.label_text)
+        # Show a short label (e.g. "Delivery time" / "Check Alive") when the
+        # user hovers the icon, so the emoji button is self-explanatory.
+        if self.tooltip_text:
+            help_button.setToolTip(_(self.tooltip_text))
         #help_button.setStyleSheet("font-size: 155555);
         hbox.addWidget(help_button)
         self.combo.currentIndexChanged.connect(self.on_current_index_changed)
@@ -422,6 +427,7 @@ class ThresholdTimeWidget(BalTimeEditWidget):
     )
     label_text = "🚨"
     #label_text = "Check Alive"
+    tooltip_text = "Check Alive"
     base_field = "threshold"
 
     def __init__(self, bal_window, parent, init_value=None):
@@ -442,6 +448,7 @@ class LockTimeWidget(BalTimeEditWidget):
     )
     label_text = "🚛"
     #label_text = "Locktime"
+    tooltip_text = "Delivery time"
     base_field = "locktime"
 
     def __init__(self, bal_window, parent, init_value=None):
@@ -468,6 +475,8 @@ class WillSettingsWidget(QWidget):
                 self.bal_window.bal_plugin.read_file("icons/calendar.png")
             )
         )
+        # Tooltip so the icon is self-explanatory when hovered.
+        self.calendar_button.setToolTip(_("Calendar"))
         self.calendar_button.clicked.connect(self.open_or_save_calendar)
         self.widgets["locktime"] = LockTimeWidget(bal_window, self)
         self.widgets["threshold"] = ThresholdTimeWidget(bal_window, self)