fix(lint): resolve all errcheck violations in ingestion module

ingestion/internal/pipeline/pipeline_test.go

@@ -37,7 +37,7 @@ func TestRun_WritesPages(t *testing.T) {
 
 	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		w.Header().Set("Content-Type", "application/json")
-		json.NewEncoder(w).Encode(map[string]any{
+		_ = json.NewEncoder(w).Encode(map[string]any{
 			"choices": []map[string]any{
 				{"message": map[string]any{"role": "assistant", "content": llmResponse}},
 			},
@@ -77,7 +77,7 @@ func TestRun_DryRunDoesNotWrite(t *testing.T) {
 	}})
 
 	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		json.NewEncoder(w).Encode(map[string]any{
+		_ = json.NewEncoder(w).Encode(map[string]any{
 			"choices": []map[string]any{{"message": map[string]any{"content": llmResponse}}},
 		})
 	}))
@@ -105,7 +105,7 @@ func TestRun_MergesDuplicatePaths(t *testing.T) {
 	})
 
 	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		json.NewEncoder(w).Encode(map[string]any{
+		_ = json.NewEncoder(w).Encode(map[string]any{
 			"choices": []map[string]any{{"message": map[string]any{"content": llmResponse}}},
 		})
 	}))