style: apply ruff's automatic fixes and formatter

Mechanical only, and separated from the judgment calls that follow so the
reviewable changes are not buried in a 98-file whitespace diff.

227 automatic fixes: 60 blank lines carrying whitespace, 60 unsorted import
blocks, 34 Optional[X] to X | None, 28 unused imports, 16 deprecated typing
imports, 12 datetime.timezone.utc to datetime.UTC, and assorted smaller
modernisations. Then `ruff format` over src and tests: 98 files reformatted,
35 already conforming.

No file among the unused-import findings defines __all__ or is an __init__.py,
so nothing here removes a re-export.

`make test`: 658 passed, unchanged from HEAD.

Two things observed while verifying, neither addressed here:

`pytest tests/` cannot collect — tests/e2e/test_orchestration_e2e.py uses an
`e2e` marker that is not registered, and the config is strict about markers.
This fails identically at HEAD, so it predates this change; `make test` passes
because it ignores tests/e2e, tests/integration and tests/contracts.

test_tatlock_tool_call_logging_calculator is flaky. It failed once in a full run
with these changes and passed on the next, passes in isolation with them, and
fails in isolation at HEAD. It is order- or timing-dependent, not a regression
from this commit — established by running the full suite both ways rather than
by reasoning about which change could have caused it.

Co-Authored-By: Claude <noreply@anthropic.com>

src/responses/context.py

@@ -6,6 +6,7 @@ Handles:
 - Context trimming to fit model limits
 - Reserve tokens for output generation
 """
+
 from typing import Any
 
 
@@ -59,11 +60,7 @@ class ContextWindow:
         # Approximate: 4 characters per token
         return total_chars // 4
 
-    async def trim_to_fit(
-        self,
-        items: list[Any],
-        reserve_tokens: int = 512
-    ) -> list[Any]:
+    async def trim_to_fit(self, items: list[Any], reserve_tokens: int = 512) -> list[Any]:
         """
         Trim items to fit within context window.
 
@@ -102,11 +99,7 @@ class ContextWindow:
 
         return kept_items
 
-    async def fits_in_context(
-        self,
-        items: list[Any],
-        reserve_tokens: int = 512
-    ) -> bool:
+    async def fits_in_context(self, items: list[Any], reserve_tokens: int = 512) -> bool:
         """
         Check if items fit within context window.
 
@@ -121,11 +114,7 @@ class ContextWindow:
         available_tokens = self.max_tokens - reserve_tokens
         return total_tokens <= available_tokens
 
-    async def get_usage_stats(
-        self,
-        items: list[Any],
-        reserve_tokens: int = 512
-    ) -> dict:
+    async def get_usage_stats(self, items: list[Any], reserve_tokens: int = 512) -> dict:
         """
         Get context window usage statistics.
 
@@ -153,7 +142,7 @@ class ContextWindow:
             "reserved_tokens": reserve_tokens,
             "available_tokens": available_tokens,
             "usage_percent": round(usage_percent, 2),
-            "fits": total_tokens <= available_tokens
+            "fits": total_tokens <= available_tokens,
         }
 
     # ========================================================================