fix(provider): detect source code drift and validate package/function references

terraform/provider/internal/resources/package_resource_test.go

@@ -2,7 +2,9 @@ package resources
 
 import (
 	"context"
+	"crypto/sha256"
 	"encoding/base64"
+	"fmt"
 	"os"
 	"path/filepath"
 	"testing"
@@ -113,6 +115,16 @@ func TestResolveNamespace(t *testing.T) {
 	}
 }
 
+func TestCalculateCodeHash(t *testing.T) {
+	input := []byte("def main():\n    return 'ok'\n")
+	got := calculateCodeHash(input)
+
+	expected := fmt.Sprintf("%x", sha256.Sum256(input))
+	if got != expected {
+		t.Fatalf("unexpected code hash: got %q want %q", got, expected)
+	}
+}
+
 func TestUnstructuredToPackageModelSetsNullComputed(t *testing.T) {
 	obj := &unstructured.Unstructured{Object: map[string]interface{}{
 		"apiVersion": "fission.io/v1",