Fix integration test file path handling for GitHub Actions

Fixed the integration tests to use absolute paths when creating
temporary activity YAML files in the research directory.

The tests were failing in GitHub Actions with "unable to open database
file" errors because they used relative paths (Path("research")) which
didn't work correctly in the GitHub Actions working directory.

Changes:
- Use Path(__file__).parent.parent.parent to get absolute base directory
- Apply absolute path to both file creation and cleanup operations
- All 9 integration tests pass locally

This ensures tests work consistently across local development and
GitHub Actions environments.

tests/integration/test_app_activity_functions.py

@@ -91,8 +91,9 @@ class TestFlaskAppActivityFunctions(unittest.TestCase):
 
     def create_test_activity_file(self, content):
         """Create a temporary activity YAML file"""
-        # Ensure research directory exists
-        research_dir = Path("research")
+        # Get absolute path to research directory
+        base_dir = Path(__file__).parent.parent.parent
+        research_dir = base_dir / "research"
         research_dir.mkdir(exist_ok=True)
 
         # Create temporary file in research directory
@@ -146,7 +147,8 @@ sections:
 
         finally:
             # Clean up
-            os.unlink(Path("research") / activity_file)
+            base_dir = Path(__file__).parent.parent.parent
+            os.unlink(base_dir / "research" / activity_file)
 
     def test_start_activity_integration(self):
         """Test starting an activity with real database operations"""
@@ -207,7 +209,8 @@ sections:
 
         finally:
             # Clean up
-            os.unlink(Path("research") / activity_file)
+            base_dir = Path(__file__).parent.parent.parent
+            os.unlink(base_dir / "research" / activity_file)
 
     def test_handle_activity_response_integration(self):
         """Test handling activity responses with real categorization and database updates"""
@@ -280,7 +283,8 @@ sections:
 
         finally:
             # Clean up
-            os.unlink(Path("research") / activity_file)
+            base_dir = Path(__file__).parent.parent.parent
+            os.unlink(base_dir / "research" / activity_file)
 
     def test_display_activity_metadata_integration(self):
         """Test displaying activity metadata with real database state"""