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/buildinfo/buildinfo_test.go

@@ -0,0 +1,32 @@
+package buildinfo
+
+import "testing"
+
+func TestCurrentAppliesFallbacks(t *testing.T) {
+	originalVersion, originalTagName, originalCommit, originalBuildDate := Version, TagName, Commit, BuildDate
+	t.Cleanup(func() {
+		Version = originalVersion
+		TagName = originalTagName
+		Commit = originalCommit
+		BuildDate = originalBuildDate
+	})
+
+	Version = ""
+	TagName = ""
+	Commit = ""
+	BuildDate = ""
+
+	info := Current()
+	if info.Version != "dev" {
+		t.Fatalf("version = %q, want %q", info.Version, "dev")
+	}
+	if info.TagName != "dev" {
+		t.Fatalf("tag_name = %q, want %q", info.TagName, "dev")
+	}
+	if info.Commit != "unknown" {
+		t.Fatalf("commit = %q, want %q", info.Commit, "unknown")
+	}
+	if info.BuildDate != "unknown" {
+		t.Fatalf("build_date = %q, want %q", info.BuildDate, "unknown")
+	}
+}