core: extract GUI-free logic into bal.core (reminders/checkalive/input_rules); fix save/sign tx RLock pickle by serializing tx; keep invalid heirs in wallet on build; tb1 testnet will-executor addresses; move tests to core modules

tests/test_group_d_alarms.py

@@ -10,13 +10,12 @@ Covered behaviour:
     most one reminder per available day, and never returns more reminders than
     requested.
 
-``compute_reminder_offsets`` lives in ``bal.gui.qt.widgets`` (which imports
-PyQt6), so these tests are run headless with ``QT_QPA_PLATFORM=offscreen`` like
-the other GUI tests.
+``compute_reminder_offsets`` now lives in ``bal.core.reminders`` (pure, GUI-free),
+so these tests run without Qt (or Electrum) at all.
 
 Run:
-    QT_QPA_PLATFORM=offscreen PYTHONPATH=electrum-src \
-        python3 -m pytest tests/test_group_d_alarms.py -q
+    source /home/steal/devel/bal/electrum/env/bin/activate
+    python3 tests/test_group_d_alarms.py
 """
 
 import os
@@ -25,7 +24,7 @@ import sys
 sys.path.insert(0, os.path.join(os.path.dirname(__file__), os.pardir))
 
 from bal.core.plugin_base import BalConfig
-from bal.gui.qt.widgets import compute_reminder_offsets
+from bal.core.reminders import compute_reminder_offsets
 
 # ------------------------------------------------------------------ #
 # Mocks