Fix ruff lint findings across client, protocol, and tests

Resolve 51 findings from the I/RUF/BLE/TRY002/S110/PLR0402 rule set:

- Sort imports and __all__ (I001, RUF022, PLR0402). The sys.path.insert
  calls in check_public_calls.py and tests/test_e2e.py still precede the
  openttd imports that depend on them.
- Replace unused unpacked values with _ (RUF059) and annotate the two
  timetable lookup tables as ClassVar (RUF012).
- Narrow the best-effort excepts in OpenTTDClient.quit and
  OpenTTDAdminClient.quit to (OSError, SocketClosed) and log at debug
  rather than swallowing silently (BLE001, S110). The test doubles now
  raise an OSError subclass so they still exercise that branch.
- Narrow the gamescript JSON fallback to json.JSONDecodeError. The broad
  catch in receive_packet keeps a noqa: it guards untrusted wire data and
  must degrade to a no-op packet instead of killing the connection.
- Use contextlib.suppress instead of try/except/pass in tests.

ruff check . is clean, 102 tests pass, coverage stays at 100%.

Co-Authored-By: Claude <[email protected]>

tests/test_protocol.py

@@ -1,9 +1,12 @@
-import pytest
+import contextlib
 import struct
+
 import monocypher
+import pytest
 from openttd.protocol import OpenTTDProtocol, PacketGameType
 from openttd_protocol.wire.exceptions import SocketClosed
 
+
 class MockTransport:
     def __init__(self): self._closing = False
     def is_closing(self): return self._closing
@@ -59,10 +62,8 @@ def test_protocol_static_parsers():
     assert OpenTTDProtocol.receive_ServerNeedCompanyPassword(None, memoryview(struct.pack("<I", 1234) + b"sid\x00")) == {"seed": 1234, "server_id": "sid"}
     
     # Coverage for receive_ServerGameInfo
-    try:
+    with contextlib.suppress(Exception):
         OpenTTDProtocol.receive_ServerGameInfo(None, memoryview(b"\x00" * 200))
-    except Exception:
-        pass
 
 @pytest.mark.asyncio
 async def test_protocol_exception_handling():
@@ -71,7 +72,7 @@ async def test_protocol_exception_handling():
     proto.transport = MockTransport()
     
     # Passing data that causes struct.unpack to fail (too short for uint16)
-    ptype, kwargs = proto.receive_packet(None, memoryview(b"\x01"))
+    ptype, _ = proto.receive_packet(None, memoryview(b"\x01"))
     assert ptype == PacketGameType.ServerUnused
 
 @pytest.mark.asyncio
@@ -111,8 +112,8 @@ async def test_protocol_decryption_failure():
     proto.transport = MockTransport()
     
     # Needs to be at least 18 bytes for read_uint16 + mac
-    wire_data = memoryview(b"\x14\x00" + b"X" * 16 + b"junk") 
-    ptype, kwargs = proto.receive_packet(None, wire_data)
+    wire_data = memoryview(b"\x14\x00" + b"X" * 16 + b"junk")
+    ptype, _ = proto.receive_packet(None, wire_data)
     assert ptype == PacketGameType.ServerUnused
 
 @pytest.mark.asyncio
@@ -127,9 +128,10 @@ async def test_protocol_is_closing_failure():
         await proto.send_packet(b"\x02\x00")
 
 def test_admin_protocol_static_receives():
-    from openttd.protocol import OpenTTDAdminProtocol
     import struct
 
+    from openttd.protocol import OpenTTDAdminProtocol
+
     # 1. receive_ServerProtocol
     data = memoryview(struct.pack("<B B H H B", 3, 1, 10, 100, 0))
     res = OpenTTDAdminProtocol.receive_ServerProtocol(None, data)