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/widgets.py

@@ -347,12 +347,16 @@ class LockTimeRawEdit(QLineEdit, _LockTimeEditor):
         self.textChanged.connect(self.numbify)
         self.isdays = False
         self.isyears = False
-        self.isblocks = False
         self.time_edit = time_edit
 
     @staticmethod
     def replace_str(text):
-        return str(text).replace("d", "").replace("y", "").replace("b", "")
+        """Strip the relative-time suffixes (d/y) from the text.
+
+        Only days ("d") and years ("y") are supported. The block-height
+        suffix ("b") was removed (A1): locktimes are always timestamps now.
+        """
+        return str(text).replace("d", "").replace("y", "")
 
     def checkbdy(self, s, pos, appendix):
         try:
@@ -367,33 +371,29 @@ class LockTimeRawEdit(QLineEdit, _LockTimeEditor):
         return pos, s
 
     def numbify(self):
+        # Only digits plus the day ("d") and year ("y") suffixes are accepted.
+        # The block-height suffix ("b") was removed (A1): locktimes are always
+        # UNIX timestamps now, so block-relative input is no longer allowed.
         text = self.text().strip()
-        # chars = '0123456789bdy' removed the option to choose locktime by block
         chars = "0123456789dy"
         pos = self.cursorPosition()
         pos = len("".join([i for i in text[:pos] if i in chars]))
         s = "".join([i for i in text if i in chars])
         self.isdays = False
         self.isyears = False
-        self.isblocks = False
 
         pos, s = self.checkbdy(s, pos, "d")
         pos, s = self.checkbdy(s, pos, "y")
-        pos, s = self.checkbdy(s, pos, "b")
 
         if "d" in s:
             self.isdays = True
         if "y" in s:
             self.isyears = True
-        if "b" in s:
-            self.isblocks = True
 
         if self.isdays:
             s = self.replace_str(s) + "d"
         if self.isyears:
             s = self.replace_str(s) + "y"
-        if self.isblocks:
-            s = self.replace_str(s) + "b"
         self.blockSignals(True)
         self.setText(s)
         self.blockSignals(False)
@@ -420,6 +420,11 @@ class LockTimeRawEdit(QLineEdit, _LockTimeEditor):
 
 
 class LockTimeDateEdit(QDateTimeEdit, _LockTimeEditor):
+    # GUARD (kept on purpose, A1): NLOCKTIME_BLOCKHEIGHT_MAX is the highest value
+    # Bitcoin interprets as a *block height*. By forcing the minimum to one above
+    # it, every locktime entered here is guaranteed to be a UNIX *timestamp*,
+    # never a block height. This is NOT block-height ordering; it is the
+    # "bouncer" that prevents block-height values from ever being used again.
     min_allowed_value = NLOCKTIME_BLOCKHEIGHT_MAX + 1
     max_allowed_value = _LockTimeEditor.get_max_allowed_timestamp()