fix(osmosis): the MsgSend client path was dead code with three bugs

Adding the first Osmosis device tests immediately failed with
"Unsupported denomination: uosmo". The cause is that osmosis_sign_tx's
MsgSend branch had never executed:

1. It whitelisted 'uatom' — the COSMOS denom. Osmosis's native denom is
   uosmo, so signing a plain OSMO transfer was impossible.
2. It never forwarded the denom, though OsmosisMsgSend carries one. The
   firmware needs it to decide whether to scale (uosmo -> OSMO) or show raw
   base units.
3. It assigned amount=int(...) to OsmosisMsgSend.amount, which is a STRING
   field — that alone would have raised for uatom too.

Bug 3 proves the path never ran; bugs 1 and 2 are why it went unnoticed.

No denom whitelist belongs on the client: the firmware already handles any
denom, scaling uosmo and showing everything else as raw base units precisely
so it never guesses a precision it does not know.

Author: BitHighlander

keepkeylib/client.py

@@ -999,15 +999,20 @@ def osmosis_sign_tx(
                 if len(msg['value']['amount']) != 1:
                     raise CallException("Osmosis.MsgSend", "Multiple amounts per msg not supported")
 
-                denom = msg['value']['amount'][0]['denom']
-                if denom != 'uatom':
-                    raise CallException("Osmosis.MsgSend", "Unsupported denomination: " + denom)
-
+                # This branch had never executed. It whitelisted 'uatom' — the
+                # COSMOS denom, so a native OSMO send was impossible — dropped
+                # the denom instead of forwarding it, and assigned an int to
+                # OsmosisMsgSend.amount, which is a string field and would have
+                # raised even for uatom. No denom whitelist belongs here at all:
+                # the firmware decides how to render each one (uosmo scaled to
+                # OSMO, anything else shown as raw base units).
+                coin = msg['value']['amount'][0]
                 resp = self.call(osmosis_proto.OsmosisMsgAck(
                     send=osmosis_proto.OsmosisMsgSend(
                         from_address=msg['value']['from_address'],
                         to_address=msg['value']['to_address'],
-                        amount=int(msg['value']['amount'][0]['amount']),
+                        denom=coin['denom'],
+                        amount=str(coin['amount']),
                         address_type=types.SPEND,
                     )
                 ))