refactor: remove field-shadowing of TargetCustomizationMode in FleetYAML

FleetYAML was declaring its own TargetCustomizationMode field with
the same JSON tag as the embedded BundleSpec.TargetCustomizationMode,
causing field shadowing and requiring manual propagation.

Since FleetYAML embeds BundleSpec, the field is already accessible
and YAML unmarshalling works correctly without duplication.

Fixes Copilot review comments in PR rancher#4940.

Changes:
- Remove duplicate TargetCustomizationMode field from FleetYAML
- Remove manual copy in bundleFromDir()
- Update test comment to reflect unmarshalling via embedded struct

Author: p-se

internal/bundlereader/read.go

@@ -189,7 +189,6 @@ func bundleFromDir(ctx context.Context, name, baseDir string, bundleData []byte,
 		tc.Source = "customization"
 		fy.Targets = append(fy.Targets, tc)
 	}
-	fy.BundleSpec.TargetCustomizationMode = fy.TargetCustomizationMode
 
 	meta, err := readMetadata(bundleData)
 	if err != nil {

internal/bundlereader/read_test.go

@@ -11,8 +11,8 @@ import (
 )
 
 // TestBundleFromDir_TargetCustomizationModePropagate verifies that the
-// targetCustomizationMode field from fleet.yaml is copied into
-// bundle.Spec.TargetCustomizationMode by bundleFromDir.
+// targetCustomizationMode field from fleet.yaml is correctly unmarshalled into
+// bundle.Spec.TargetCustomizationMode via the embedded BundleSpec.
 func TestBundleFromDir_TargetCustomizationModePropagate(t *testing.T) {
 	dir := t.TempDir()
 

pkg/apis/fleet.cattle.io/v1alpha1/fleetyaml.go

@@ -10,12 +10,6 @@ type FleetYAML struct {
 	// dependsOn.selector.
 	Labels map[string]string `json:"labels,omitempty"`
 	BundleSpec
-	// TargetCustomizationMode controls how targetCustomizations are evaluated.
-	// "FirstMatch" (default) stops at the first matching entry.
-	// "AllMatches" applies all matching entries in order, merging them.
-	// +kubebuilder:default=FirstMatch
-	// +kubebuilder:validation:Enum=FirstMatch;AllMatches
-	TargetCustomizationMode TargetCustomizationMode `json:"targetCustomizationMode,omitempty"`
 	// TargetCustomizations are used to determine how resources should be
 	// modified per target. Targets are evaluated in order. By default
 	// (FirstMatch) the first one to match a cluster is used for that cluster.