⚡ Add slice pre-allocation optimizations

Optimize slice allocations in boxcutter to reduce memory overhead:

1. Pre-allocate trimmedPrevious with ClusterExtensionRevisionPreviousLimit capacity
   - Avoids reallocation as the slice grows

2. Smart pre-allocation in splitManifestDocuments
   - Estimates document count based on line count
   - Reduces allocations when processing large helm manifests
   - Minimum capacity of 4 for small bundles

These micro-optimizations reduce GC pressure during revision processing.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: tmshort

internal/operator-controller/applier/boxcutter.go

@@ -335,7 +335,8 @@ func (bc *Boxcutter) apply(ctx context.Context, contentFS fs.FS, ext *ocv1.Clust
 // ClusterExtensionRevisionPreviousLimit or to the first _active_ revision and deletes trimmed revisions from the cluster.
 // NOTE: revisionList must be sorted in chronographical order, from oldest to latest.
 func (bc *Boxcutter) setPreviousRevisions(ctx context.Context, latestRevision *ocv1.ClusterExtensionRevision, revisionList []ocv1.ClusterExtensionRevision) error {
-	trimmedPrevious := make([]ocv1.ClusterExtensionRevisionPrevious, 0)
+	// Pre-allocate with capacity limit to reduce allocations
+	trimmedPrevious := make([]ocv1.ClusterExtensionRevisionPrevious, 0, ClusterExtensionRevisionPreviousLimit)
 	for index, r := range revisionList {
 		if index < len(revisionList)-ClusterExtensionRevisionPreviousLimit && r.Spec.LifecycleState == ocv1.ClusterExtensionRevisionLifecycleStateArchived {
 			// Delete oldest CREs from the cluster and list to reach ClusterExtensionRevisionPreviousLimit or latest active revision
@@ -377,9 +378,16 @@ func latestRevisionNumber(prevRevisions []ocv1.ClusterExtensionRevision) int64 {
 }
 
 func splitManifestDocuments(file string) []string {
-	//nolint:prealloc
-	var docs []string
-	for _, manifest := range strings.Split(file, "\n") {
+	// Estimate: typical manifests have ~50-100 lines per document
+	// Pre-allocate for reasonable bundle size to reduce allocations
+	lines := strings.Split(file, "\n")
+	estimatedDocs := len(lines) / 20 // conservative estimate
+	if estimatedDocs < 4 {
+		estimatedDocs = 4
+	}
+	docs := make([]string, 0, estimatedDocs)
+
+	for _, manifest := range lines {
 		manifest = strings.TrimSpace(manifest)
 		if len(manifest) == 0 {
 			continue