Handle ambiguous futes contracts in `get_fute()`

Use (the only available in `ib_async`) `returnAll=True` in
`qualifyContractsAsync()` calls within `get_fute()` and handle the case
where IB returns a list of ambiguous contract matches instead of
a single result.

Deats,
- add `returnAll=True` to both `ContFuture` and `Future`
  qualification calls.
- add `isinstance(con, list)` check after unpacking first result
  to detect ambiguous contract sets.
- log warning with input params and matched contracts when
  ambiguous.
- update return type annot to `Contract|list[Contract]`.

Also,
- handle list-of-contracts case in `find_contracts()` by unpacking
  `*contracts` into the `qualifyContractsAsync()` call.
- reformat `qualifyContractsAsync()` calls to multiline style.

(this commit msg was generated in some part by [`claude-code`][claude-code-gh])
[claude-code-gh]: https://github.com/anthropics/claude-code

piker/brokers/ib/api.py

@@ -768,26 +768,48 @@ class Client:
         expiry: str = '',
         front: bool = False,
 
-    ) -> Contract:
+    ) -> Contract|list[Contract]:
         '''
         Get an unqualifed contract for the current "continous"
         future.
 
+        When input params result in a so called "ambiguous contract"
+        situation, we return the list of all matches provided by,
+
+        `IB.qualifyContractsAsync(..., returnAll=True)`
+
         '''
         # it's the "front" contract returned here
         if front:
-            con = (await self.ib.qualifyContractsAsync(
-                ContFuture(symbol, exchange=exchange)
-            ))[0]
-        else:
-            cons = (await self.ib.qualifyContractsAsync(
-                Future(
-                    symbol,
-                    exchange=exchange,
-                    lastTradeDateOrContractMonth=expiry,
+            cons = (
+                await self.ib.qualifyContractsAsync(
+                    ContFuture(symbol, exchange=exchange),
+                    returnAll=True,
                 )
-            ))
-            con = cons[0]
+            )
+        else:
+            cons = (
+                await self.ib.qualifyContractsAsync(
+                    Future(
+                        symbol,
+                        exchange=exchange,
+                        lastTradeDateOrContractMonth=expiry,
+                    ),
+                    returnAll=True,
+                )
+            )
+
+        con = cons[0]
+        if isinstance(con, list):
+            log.warning(
+                f'{len(con)!r} futes cons matched for input params,\n'
+                f'symbol={symbol!r}\n'
+                f'exchange={exchange!r}\n'
+                f'expiry={expiry!r}\n'
+                f'\n'
+                f'cons:\n'
+                f'{con!r}\n'
+            )
 
         return con
 
@@ -912,11 +934,17 @@ class Client:
             )
             exch = 'SMART' if not exch else exch
 
-        contracts: list[Contract] = [con]
+        if isinstance(con, list):
+            contracts: list[Contract] = con
+        else:
+            contracts: list[Contract] = [con]
+
         if qualify:
             try:
                 contracts: list[Contract] = (
-                    await self.ib.qualifyContractsAsync(con)
+                    await self.ib.qualifyContractsAsync(
+                        *contracts
+                    )
                 )
             except RequestError as err:
                 msg = err.message