core+gui+cli: anticipation/rebuild dates, preserve relative settings

Fixes around the delivery/build/check date handling (karen7 regtest):

- build_will (GUI + CLI) re-anchors date_to_check to the CURRENT heirs'
  earliest future delivery before building, so an anticipated rebuild is no
  longer blocked by the stale old-will anchor (NO_FUTURE_DATE). The checks of
  the existing will keep their anchored date_to_check.
- _sync_locktime_to_built_txs now PRESERVES RELATIVE locktime/threshold
  recipes ("2y"/"150d") in WILL_SETTINGS instead of freezing them to absolute
  timestamps: the anchored comparisons (resolve_locktime_against_tx and
  resolve_date_to_check with built_locktime) already prevent the daily
  invalidate prompt. Absolute values still sync on a genuine automatic
  anticipation.
- Will.remove_stale_wallet_history drops stale wallet-LOCAL will placeholders
  before every (re)build in GUI and CLI so their coins are available again.
- check_willexecutors_and_heirs raises HeirNotFoundException outside the
  count_heirs gate: a shortened relative recipe on a signed will now triggers
  a plain rebuild ("no heirs" only when there really are none).
- is_locktime_below_threshold compares the settings on one reference frame
  (resolve_guard_threshold), no longer against the built-will anchor.

Tests: purge unit + call-site, no-heirs, guard, anticipated-rebuild
end-to-end (GUI) + CLI mirror + fixed_percent_lists_amount unit,
relative-preserve sync; conftest restores electrum.constants.net after each
test (cross-file pollution guard).

tests/test_cli_controller_offline.py

@@ -18,6 +18,7 @@ import shutil
 import sys
 import tempfile
 import time
+import unittest.mock as mock
 
 sys.path.insert(0, os.path.join(os.path.dirname(__file__), os.pardir))
 
@@ -25,6 +26,8 @@ from electrum.simple_config import SimpleConfig
 from electrum.util import UserFacingException
 
 from bal.cli.controller import BalController
+from bal.core.heirs import Heirs
+from bal.core.util import Util
 
 VALID_ADDRESS = "bc1qusymuetsz2psaqzqxv8qmzcy64d9meckj3lxxf"
 
@@ -227,6 +230,39 @@ def test_auto_rebuild_threshold_passed_invalidates():
         assert result["invalidation_tx"] == {"txid": None, "tx": None}
 
 
+def test_build_will_reanchors_date_to_check_to_new_locktime():
+    """CLI mirror of the GUI regression: ``build_will`` must re-anchor
+    ``date_to_check`` to the CURRENT heirs' earliest delivery before building,
+    so an anticipated (shortened) rebuild is not blocked by the old built-will
+    anchor (which would yield NO_FUTURE_DATE in ``get_transactions``).
+    """
+    with Plugin() as plugin:
+        plugin.USER_TYPE.set("advanced")
+        plugin.NO_WILLEXECUTOR.set(True)
+        plugin.ENABLE_MULTIVERSE.set(True)
+        plugin.WILL_SETTINGS.set({"threshold": "150d", "locktime": "2y", "baltx_fees": 20})
+        c = _make_controller(plugin)
+        c.no_willexecutor = True
+        c.heirs["alice"] = [VALID_ADDRESS, "100%", "1y"]
+
+        # Simulate an old built will frozen at 2y: reload keeps its (stale)
+        # anchor, which would reject the anticipated "1y" delivery.
+        c.init_class_variables()
+        stale_anchor = Util.parse_locktime_string("2y") - 150 * 86400
+        c.date_to_check = stale_anchor
+        assert Util.parse_locktime_string("1y") < c.date_to_check
+
+        with mock.patch.object(Heirs, "get_transactions", return_value={}) as gt:
+            result = c.build_will()
+
+        assert result == {}
+        # build_will re-anchored date_to_check to the new 1y delivery...
+        expected = Util.parse_locktime_string("1y") - 150 * 86400
+        assert abs(c.date_to_check - expected) < 3600
+        # ...and used THAT anchor as the build filter, not the stale 2y one.
+        assert gt.call_args.args[-1] == c.date_to_check
+
+
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