build(lint): configure isort known-first-party for deterministic import grouping

Without explicit known-first-party, ruff classifies coordinode as third-party
when the package is not installed as editable (e.g. plain `uv sync` in the
lint job). This caused inconsistent blank-line requirements across test files.
Setting known-first-party ensures consistent import grouping regardless of the
install state.

Author: polaz

ruff.toml

@@ -13,3 +13,6 @@ select = ["E", "F", "I", "W", "UP"]
 ignore = [
     "E501",  # line length handled by formatter
 ]
+
+[lint.isort]
+known-first-party = ["coordinode", "langchain_coordinode", "llama_index_coordinode"]

tests/unit/test_types.py

@@ -6,6 +6,7 @@
 """
 
 import pytest
+
 from coordinode._types import from_property_value, to_property_value
 
 # Detect whether proto stubs have been generated.