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/agents/tools.py

@@ -13,11 +13,11 @@ import math
 import re
 from datetime import datetime, timedelta
 
-
 # ============================================================================
 # Calculator Tool
 # ============================================================================
 
+
 def calculate(expression: str) -> str:
     """
     Safely evaluate mathematical expressions.
@@ -46,33 +46,29 @@ def calculate(expression: str) -> str:
         # Create safe namespace with math functions
         safe_dict = {
             # Basic math functions
-            'sqrt': math.sqrt,
-            'pow': math.pow,
-            'abs': abs,
-            'round': round,
-
+            "sqrt": math.sqrt,
+            "pow": math.pow,
+            "abs": abs,
+            "round": round,
             # Trigonometric
-            'sin': math.sin,
-            'cos': math.cos,
-            'tan': math.tan,
-            'asin': math.asin,
-            'acos': math.acos,
-            'atan': math.atan,
-
+            "sin": math.sin,
+            "cos": math.cos,
+            "tan": math.tan,
+            "asin": math.asin,
+            "acos": math.acos,
+            "atan": math.atan,
             # Logarithmic
-            'log': math.log,
-            'log10': math.log10,
-            'log2': math.log2,
-            'exp': math.exp,
-
+            "log": math.log,
+            "log10": math.log10,
+            "log2": math.log2,
+            "exp": math.exp,
             # Other
-            'ceil': math.ceil,
-            'floor': math.floor,
-            'factorial': math.factorial,
-
+            "ceil": math.ceil,
+            "floor": math.floor,
+            "factorial": math.factorial,
             # Constants
-            'pi': math.pi,
-            'e': math.e,
+            "pi": math.pi,
+            "e": math.e,
         }
 
         # Evaluate the expression safely
@@ -97,6 +93,7 @@ def calculate(expression: str) -> str:
 # Date/Time Toolkit
 # ============================================================================
 
+
 def get_current_datetime(format_str: str = "full") -> str:
     """
     Get the current date and time.
@@ -157,7 +154,7 @@ def calculate_time_offset(offset_description: str) -> str:
 
         # Parse the offset description
         # Pattern: "N unit(s) ago/from now"
-        pattern = r'(\d+)\s+(second|minute|hour|day|week|month|year)s?\s+(ago|from\s+now)'
+        pattern = r"(\d+)\s+(second|minute|hour|day|week|month|year)s?\s+(ago|from\s+now)"
         match = re.match(pattern, offset_description.lower().strip())
 
         if not match: