Add benchmark tests and optimize encryption performance

- Introduced comprehensive benchmark tests for NIP-44 and NIP-4 encryption/decryption, including various message sizes and round-trip operations.
- Implemented optimizations to reduce memory allocations and CPU processing time in encryption functions, focusing on pre-allocating buffers and minimizing reallocations.
- Enhanced error handling in encryption and decryption processes to ensure robustness.
- Documented performance improvements in the new PERFORMANCE_REPORT.md file, highlighting significant reductions in execution time and memory usage.

pkg/encoders/text/helpers.go

@@ -139,15 +139,27 @@ func UnmarshalQuoted(b []byte) (content, rem []byte, err error) {
 }
 
 func MarshalHexArray(dst []byte, ha [][]byte) (b []byte) {
-	dst = append(dst, '[')
+	b = dst
+	// Pre-allocate buffer if nil to reduce reallocations
+	// Estimate: [ + (hex encoded item + quotes + comma) * n + ]
+	// Each hex item is 2*size + 2 quotes = 2*size + 2, plus comma for all but last
+	if b == nil && len(ha) > 0 {
+		estimatedSize := 2 // brackets
+		if len(ha) > 0 {
+			// Estimate based on first item size
+			itemSize := len(ha[0]) * 2 // hex encoding doubles size
+			estimatedSize += len(ha) * (itemSize + 2 + 1) // item + quotes + comma
+		}
+		b = make([]byte, 0, estimatedSize)
+	}
+	b = append(b, '[')
 	for i := range ha {
-		dst = AppendQuote(dst, ha[i], hex.EncAppend)
+		b = AppendQuote(b, ha[i], hex.EncAppend)
 		if i != len(ha)-1 {
-			dst = append(dst, ',')
+			b = append(b, ',')
 		}
 	}
-	dst = append(dst, ']')
-	b = dst
+	b = append(b, ']')
 	return
 }
 
@@ -156,6 +168,9 @@ func MarshalHexArray(dst []byte, ha [][]byte) (b []byte) {
 func UnmarshalHexArray(b []byte, size int) (t [][]byte, rem []byte, err error) {
 	rem = b
 	var openBracket bool
+	// Pre-allocate slice with estimated capacity to reduce reallocations
+	// Estimate based on typical array sizes (can grow if needed)
+	t = make([][]byte, 0, 16)
 	for ; len(rem) > 0; rem = rem[1:] {
 		if rem[0] == '[' {
 			openBracket = true
@@ -193,6 +208,9 @@ func UnmarshalHexArray(b []byte, size int) (t [][]byte, rem []byte, err error) {
 func UnmarshalStringArray(b []byte) (t [][]byte, rem []byte, err error) {
 	rem = b
 	var openBracket bool
+	// Pre-allocate slice with estimated capacity to reduce reallocations
+	// Estimate based on typical array sizes (can grow if needed)
+	t = make([][]byte, 0, 16)
 	for ; len(rem) > 0; rem = rem[1:] {
 		if rem[0] == '[' {
 			openBracket = true