style(memory): apply ruff formatting and linting fixes

Auto-fixed linting errors and formatting issues:
- Removed unused imports (F401): pytest, Any, AnalysisType, MemoryType, OutcomeType
- Removed unused variable (F841): hooks variable in test
- Applied consistent formatting across memory service and test files

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/tests/unit/services/memory/metrics/test_collector.py

@@ -134,9 +134,7 @@ class TestMemoryMetrics:
         await metrics.set_memory_items_count("semantic", "project", 50)
 
         all_metrics = await metrics.get_all_metrics()
-        gauge_metrics = [
-            m for m in all_metrics if m.name == "memory_items_count"
-        ]
+        gauge_metrics = [m for m in all_metrics if m.name == "memory_items_count"]
 
         assert len(gauge_metrics) == 2
 
@@ -181,7 +179,11 @@ class TestMemoryMetrics:
 
         all_metrics = await metrics.get_all_metrics()
         count_metric = next(
-            (m for m in all_metrics if m.name == "memory_working_latency_seconds_count"),
+            (
+                m
+                for m in all_metrics
+                if m.name == "memory_working_latency_seconds_count"
+            ),
             None,
         )
         sum_metric = next(
@@ -204,9 +206,7 @@ class TestMemoryMetrics:
         assert summary["avg_retrieval_latency_ms"] == pytest.approx(62.5, rel=0.01)
 
     @pytest.mark.asyncio
-    async def test_observe_consolidation_duration(
-        self, metrics: MemoryMetrics
-    ) -> None:
+    async def test_observe_consolidation_duration(self, metrics: MemoryMetrics) -> None:
         """Should record consolidation duration histogram."""
         await metrics.observe_consolidation_duration(5.0)
         await metrics.observe_consolidation_duration(10.0)
@@ -236,7 +236,9 @@ class TestMemoryMetrics:
         assert len(all_metrics) >= 3
 
         # Check we have different metric types
-        counter_metrics = [m for m in all_metrics if m.metric_type == MetricType.COUNTER]
+        counter_metrics = [
+            m for m in all_metrics if m.metric_type == MetricType.COUNTER
+        ]
         gauge_metrics = [m for m in all_metrics if m.metric_type == MetricType.GAUGE]
 
         assert len(counter_metrics) >= 1