test(tools): add unit tests for error handling functions

* Implement tests for error functions like errRequiredField, errInvalidField, and errEntityNotFound.
* Ensure proper metadata is returned for various error scenarios.
* Validate error handling in CRM, Files, and other tools.
* Introduce tests for parsing stored file IDs and UUIDs.
* Enhance coverage for helper functions related to project resolution and session management.

internal/ai/compat/client_test.go

@@ -15,7 +15,9 @@ func TestExtractMetadataFromStreamingResponse(t *testing.T) {
 	t.Parallel()
 
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		defer r.Body.Close()
+		defer func() {
+			_ = r.Body.Close()
+		}()
 
 		var req chatCompletionsRequest
 		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
@@ -68,7 +70,9 @@ func TestExtractMetadataRetriesWithoutJSONMode(t *testing.T) {
 	plainCalls := 0
 
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		defer r.Body.Close()
+		defer func() {
+			_ = r.Body.Close()
+		}()
 
 		var req chatCompletionsRequest
 		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
@@ -131,7 +135,9 @@ func TestExtractMetadataBypassesInvalidFallbackModelAfterFirstFailure(t *testing
 	invalidFallbackCalls := 0
 
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		defer r.Body.Close()
+		defer func() {
+			_ = r.Body.Close()
+		}()
 
 		var req chatCompletionsRequest
 		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {