test: add DeleteImportedSessions method to mock repositories

Fixed failing tests by implementing missing DeleteImportedSessions method
in all mock SessionRepository implementations:
- mockSessionRepo (services_test.go)
- stubSessionRepo (compose_service_test.go)
- mockSessionRepoForPerformance (performance/usecase/service_test.go)

This resolves compilation errors in CI/CD pipeline where tests failed
with "missing method DeleteImportedSessions" error.

Author: 777genius

internal/features/performance/usecase/service_test.go

@@ -624,6 +624,10 @@ func (m *mockSessionRepoForPerformance) ClearAllSessions(ctx context.Context) er
 	return nil
 }
 
+func (m *mockSessionRepoForPerformance) DeleteImportedSessions(ctx context.Context) error {
+	return nil
+}
+
 type mockFrameRepoForPerformance struct{}
 
 func (m *mockFrameRepoForPerformance) AppendFrame(ctx context.Context, sessionID string, f domain.Frame) error {

internal/usecase/compose_service_test.go

@@ -99,6 +99,10 @@ func (s *stubSessionRepo) ClearAllSessions(ctx context.Context) error {
 	return nil
 }
 
+func (s *stubSessionRepo) DeleteImportedSessions(ctx context.Context) error {
+	return nil
+}
+
 type stubFrameRepo struct{}
 
 func (stubFrameRepo) AppendFrame(ctx context.Context, sessionID string, f domain.Frame) error {

internal/usecase/services_test.go

@@ -57,6 +57,10 @@ func (m *mockSessionRepo) ClearAllSessions(ctx context.Context) error {
 	return nil
 }
 
+func (m *mockSessionRepo) DeleteImportedSessions(ctx context.Context) error {
+	return nil
+}
+
 func (m *mockSessionRepo) AddSpoolFile(ctx context.Context, sessionID string, path string) {}
 
 type mockFrameRepo struct {