Handle `tractor.TransportClosed` as "stream-closed"

In both the ems and sampler since on new `tractor` this is the
"wrapping" exception raised when the transport layer terminates early
but in a psuedo-"graceful" way, expected when a peer actors disconnect.
Previously we were crashing in this case since old `tractor` just raised
the underlying `trio`-source-exceptions verbatim.

Also,
- use `Aid.reprol()` in log msgs vs old `.chan.uid` refs

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

piker/clearing/_ems.py

@@ -729,6 +729,7 @@ class Router(Struct):
             except (
                 trio.ClosedResourceError,
                 trio.BrokenResourceError,
+                tractor.TransportClosed,
             ):
                 to_remove.add(client_stream)
                 log.warning(
@@ -1699,5 +1700,5 @@ async def _emsd_main(
                     if not client_streams:
                         log.warning(
                             f'Order dialog is not being monitored:\n'
-                            f'{oid} ->\n{client_stream._ctx.chan.uid}'
+                            f'{oid!r} <-> {client_stream.chan.aid.reprol()}\n'
                         )

piker/data/_sampling.py

@@ -99,6 +99,7 @@ class Sampler:
         trio.BrokenResourceError,
         trio.ClosedResourceError,
         trio.EndOfChannel,
+        tractor.TransportClosed,
     )
 
     # holds all the ``tractor.Context`` remote subscriptions for
@@ -753,7 +754,7 @@ async def sample_and_broadcast(
                                 log.warning(
                                     f'Feed OVERRUN {sub_key}'
                                     f'@{bus.brokername} -> \n'
-                                    f'feed @ {chan.uid}\n'
+                                    f'feed @ {chan.aid.reprol()}\n'
                                     f'throttle = {throttle} Hz'
                                 )