core+gui: compact BAL QR v2 wire format + best-of compression default

BAL QR export now ships a fixed 11-char 'BAL1<TTT><iii><F><payload>' header
(3-char base36 zero-padded count fields, cap 46655 frames) and, by default,
the shorter of plain vs zlib+base64 (flag '0'/'Z'). parse_frame remains dual:
legacy 'BALQR1|total|index|flags|' frames still import. detect_format accepts
'BAL1'. New exports are not readable by builds older than this change.

Also add a will-detail test for heir/willexecutor addresses and decoded
OP_RETURN payloads. Docs updated (CHANGELOG, COMPATIBILITY, PLAN_QR_TRANSFER,
README); 345 core tests + 89 GUI tests pass.

bal/core/animated_qr.py

@@ -8,7 +8,9 @@ used to move BAL will data between devices.
 Supported wire formats (each self-describing and order-independent on
 receive):
 
-* **BALQR** (native, unchanged): ``BALQR1|total|index|flags|payload``.
+* **BALQR** (native): ``BAL1<TTT><iii><flag><payload>`` compact fixed-width
+  header (11 chars, 3-digit base36 count fields, no separators); legacy
+  ``BALQR1|total|index|flags|payload`` still imported.
 * **BC-UR v1** (BCR-2020-005 rev1 draft, May 2020)::
       ur:bytes/1of7/<bc32-digest>/<bc32-fragment>
     Fragments partition the BC32 rendering of the CBOR byte string; the
@@ -790,7 +792,7 @@ def detect_format(text: str) -> Optional[str]:
     if not text:
         return None
     lowered = text.lower()
-    if lowered.startswith("balqr"):
+    if lowered.startswith(("balqr", "bal1")):
         return "balqr"
     if text.startswith(_BBQR_PREFIX):
         return "bbqr"