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_e2e.py

@@ -1,20 +1,22 @@
 import asyncio
-import pytest
-import pytest_asyncio
-import sys
 import os
 import random
+import sys
+
+import pytest
+import pytest_asyncio
+
 # Add lib to path
 sys.path.insert(0, os.path.join(os.path.dirname(__file__), '..', 'lib'))
 
-from openttd import OpenTTDClient, OpenTTDAdminClient
+from openttd import OpenTTDAdminClient, OpenTTDClient
 from openttd.protocol import (
-    OpenTTDProtocol,
-    OpenTTDAdminProtocol,
-    AdminUpdateType,
     AdminUpdateFrequency,
+    AdminUpdateType,
+    ModifyTimetableFlags,
+    OpenTTDAdminProtocol,
+    OpenTTDProtocol,
     PacketGameType,
-    ModifyTimetableFlags
 )
 
 # These identify a vehicle/order that already exists in the local dev server's persisted
@@ -738,11 +740,11 @@ async def test_e2e_protocol_public_functions_multiple_inputs(server_config):
 
     # 2. Test receive_packet() with multiple inputs
     # Input 1: Valid packet structure (length >= 3)
-    res_type1, res_data1 = proto_game.receive_packet(None, memoryview(b"\x03\x00\x05")) # type 5 is ServerUnused
+    res_type1, _ = proto_game.receive_packet(None, memoryview(b"\x03\x00\x05")) # type 5 is ServerUnused
     assert res_type1 == PacketGameType.ServerUnused
 
     # Input 2: Invalid/short packet structure (length < 3)
-    res_type2, res_data2 = proto_game.receive_packet(None, memoryview(b"\x01"))
+    res_type2, _ = proto_game.receive_packet(None, memoryview(b"\x01"))
     assert res_type2 == PacketGameType.ServerUnused # Falls back to ServerUnused on error
 
     # 3. Test send_packet() with multiple inputs (using mock transports)