Polish dashboard UX and update README

- Wrap simulation controls in form to prevent page reruns on change
- Fix TempCo test configs to use 2+ temperature points
- Add Installation, Quick Start, and usage examples to README

src/py_dvt_ate/data/repository.py

@@ -74,6 +74,9 @@ class ITestRepository(ABC):
     def get_all_runs(self) -> list[TestRun]:
         """Retrieve all test runs, ordered by started_at descending."""
 
+    def close(self) -> None:
+        """Close repository and release resources. Optional to implement."""
+
 
 class SQLiteRepository(ITestRepository):
     """SQLite-based repository for test data.
@@ -400,3 +403,13 @@ class SQLiteRepository(ITestRepository):
                 )
                 for row in rows
             ]
+
+    def close(self) -> None:
+        """Close repository and release resources.
+
+        SQLite connections are managed via context managers and auto-close.
+        This method performs explicit cleanup for Windows file handle issues.
+        """
+        # Force garbage collection to release any lingering connections
+        import gc
+        gc.collect()