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_timetable.py

@@ -1,9 +1,18 @@
 import pytest
 from openttd import OpenTTDClient
 from openttd.protocol import (
-    OpenTTDProtocol, GameCommand, ModifyTimetableFlags, ModifyTimetableCtrlFlag,
-    OrderType, OrderNonStopFlags, OrderStopLocation, INVALID_VEH_ORDER_ID,
-    write_varuint, read_varuint, write_varuint_signed, read_varuint_signed
+    INVALID_VEH_ORDER_ID,
+    GameCommand,
+    ModifyTimetableCtrlFlag,
+    ModifyTimetableFlags,
+    OpenTTDProtocol,
+    OrderNonStopFlags,
+    OrderStopLocation,
+    OrderType,
+    read_varuint,
+    read_varuint_signed,
+    write_varuint,
+    write_varuint_signed,
 )
 from openttd_protocol.wire.read import read_uint8, read_uint16
 
@@ -140,10 +149,10 @@ async def test_client_change_timetable_clear_field_sets_ctrl_flag():
     client = new_client()
     await client.change_timetable(7, 3, ModifyTimetableFlags.TravelTime, 0, clear_field=True)
     parsed = decode_sent_command(client._protocol.sent[0])
-    vehicle_id, rest = read_varuint(parsed["payload"])
-    order_position, rest = read_uint16(rest)
+    _, rest = read_varuint(parsed["payload"])
+    _, rest = read_uint16(rest)
     flag, rest = read_uint8(rest)
-    value, rest = read_varuint(rest)
+    _, rest = read_varuint(rest)
     ctrl_flags, _ = read_uint8(rest)
     assert flag == ModifyTimetableFlags.TravelTime
     assert ctrl_flags == ModifyTimetableCtrlFlag.ClearField
@@ -212,7 +221,7 @@ async def test_client_add_order_insert_position_and_nonstop():
     client = new_client()
     await client.add_order(7, 6, before_position=1, non_stop=OrderNonStopFlags.NoStopAtIntermediate)
     parsed = decode_sent_command(client._protocol.sent[0])
-    vehicle_id, sel_ord, order_type, order_flags, station = _decode_insert_order_payload(parsed["payload"])
+    _, sel_ord, order_type, _, _ = _decode_insert_order_payload(parsed["payload"])
     assert sel_ord == 1  # insert before order position 1
     assert order_type == (OrderType.GotoStation
                           | (OrderStopLocation.PlatformFarEnd << 4)