feat(bal): Group A (timestamps + statuses + anticipate docs) and Group B (auto-sign) v0.3.4

Bump plugin version to 0.3.4 (manifest, __init__, plugin_base, VERSION).

GROUP A
- A1: remove block-height locktimes; the plugin now uses UNIX timestamps
  only. The NLOCKTIME_BLOCKHEIGHT_MAX guard is kept on purpose (it forces
  every locktime to be a timestamp). chk_locktime is now 2-arg; int_locktime
  and anticipate_locktime no longer accept blocks; RAW input only accepts d/y.
  Two now-dormant configs (LOCKTIME_BLOCKS, LOCKTIMEDELTA_BLOCKS) are kept with
  comments to avoid touching persisted keys.
- A2: rename PENDING -> MEMPOOL everywhere (label 'Mempool', yellow #ffce30);
  add new UPDATED status; ANTICIPATED & UPDATED keep VALID; documented
  set_status rules; backward-compat migration (old PENDING -> MEMPOOL).
- A3: clarify that anticipating to a future date only rebuilds (never
  invalidates), while only a past locktime invalidates (WillExpired). Code was
  already correct; only the comment and docs were fixed.

Colour follow-up: UPDATED lightened from #800080 to #b266b2 (more readable),
updated in theme.py, docs and the theme test.

GROUP B
- B1: verified the 'Create your will' button already opens the guided wizard
  (no code change needed).
- B2: new persisted AUTO_SIGN setting (default ON) with an 'Auto-sign on Check'
  checkbox in the settings dialog. When enabled, Check signs and broadcasts
  automatically; the wallet password is requested only for encrypted wallets.

B2 follow-up (fixes reported after testing):
- Remove the duplicate sign/broadcast cycle in lists.check(); build_will_task()
  already signs and broadcasts.
- Suppress the manual 'press Sign/Broadcast' hint and its popup when AUTO_SIGN
  is ON (kept when OFF).
- Make broadcast one-shot: removed the retry flag and the Exception('retry');
  failed will-executors stay PUSH_FAIL and are skipped (no endless retry).
  PUSHED transactions are already excluded from re-collection.

Docs: inheritance-options.md/.html and inheritance-flow.svg updated to v0.3.4.
Tests: 206 passing (new test_anticipate_manual_locktime, test_anticipate_past_locktime,
test_group_b_auto_sign; updated core/util, core/will_extra, gui/theme, gui/widgets).
CHANGELOG.md added with one numbered entry per task.

bal/gui/qt/plugin.py

@@ -389,6 +389,13 @@ class Plugin(BalPlugin):
         heir_hide_replaced = BalCheckBox(self.HIDE_REPLACED, on_multiverse_change)
 
         heir_hide_invalidated = BalCheckBox(self.HIDE_INVALIDATED, on_multiverse_change)
+
+        # Auto-sign checkbox (Group B / B2). When ticked, the "Check" action
+        # automatically signs and broadcasts the will after querying the
+        # will-executor servers. Bound to the persisted AUTO_SIGN config; the
+        # default is ON (see plugin_base.py).
+        heir_auto_sign = BalCheckBox(self.AUTO_SIGN)
+
         heir_repush = QPushButton("Rebroadcast transactions")
         heir_repush.clicked.connect(partial(self.broadcast_transactions, True))
         bal_mode = QComboBox()
@@ -410,18 +417,30 @@ class Plugin(BalPlugin):
             2,
             "Hide invalidated transactions from will detail and list",
         )
+        add_widget(
+            grid,
+            "Auto-sign on Check",
+            heir_auto_sign,
+            3,
+            (
+                "When checking, automatically sign and broadcast the will "
+                "transactions to their will-executors.\n"
+                "The wallet password is requested only if the wallet is "
+                "encrypted."
+            ),
+        )
         add_widget(
             grid,
             "Calendar App",
             BalLineEdit(self.CALENDAR_APP),
-            3,
+            4,
             "Default app used to open calendar",
         )
         add_widget(
             grid,
             "Event summary",
             BalLineEdit(self.EVENT_SUMMARY),
-            4,
+            5,
             (
                 "Default message to be used in event summary\n"
                  "Variables:\n"
@@ -432,9 +451,9 @@ class Plugin(BalPlugin):
         )
         add_widget(
             grid,
-            "Event sescription",
+            "Event description",
             BalTextEdit(self.EVENT_DESCRIPTION),
-            5,
+            6,
             (
                 "Default message to be used in event description\n"
                  "Variables:\n"