refactor(jdbc): extract LibsqlBlob and LibsqlClob

Move the two read-only Blob and Clob implementations out of
LibsqlResultSet into package-private top-level classes. Constructors
become package-private so getBlob and getClob can still build them.
Pure move: messages, checks, stream encodings, and free() semantics
are unchanged. Also drops the four imports that only the moved code
used (OutputStream, Writer, StandardCharsets, Arrays).

Author: magnusp

libsql-jdbc/src/main/java/com/github/magnusp/libsql/jdbc/LibsqlBlob.java

@@ -0,0 +1,112 @@
+package com.github.magnusp.libsql.jdbc;
+
+import java.io.ByteArrayInputStream;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.sql.Blob;
+import java.sql.SQLException;
+import java.sql.SQLFeatureNotSupportedException;
+import java.util.Arrays;
+
+    /** Read-only {@link Blob} over the materialized bytes of one result column. */
+final class LibsqlBlob implements Blob {
+
+        private byte[] bytes;
+        private boolean freed;
+
+        LibsqlBlob(byte[] bytes) {
+            this.bytes = bytes;
+        }
+
+        private byte[] data() throws SQLException {
+            if (freed) {
+                throw new SQLException("Blob has been freed");
+            }
+            return bytes;
+        }
+
+        @Override
+        public long length() throws SQLException {
+            return data().length;
+        }
+
+        @Override
+        public byte[] getBytes(long pos, int length) throws SQLException {
+            byte[] data = data();
+            if (pos < 1) {
+                throw new SQLException("Invalid position: " + pos);
+            }
+            if (length < 0) {
+                throw new SQLException("Invalid length: " + length);
+            }
+            int start = (int) Math.min(pos - 1, data.length);
+            int end = Math.min(start + length, data.length);
+            return Arrays.copyOfRange(data, start, end);
+        }
+
+        @Override
+        public InputStream getBinaryStream() throws SQLException {
+            return new ByteArrayInputStream(data());
+        }
+
+        @Override
+        public long position(byte[] pattern, long start) throws SQLException {
+            if (start < 1) {
+                throw new SQLException("Invalid position: " + start);
+            }
+            byte[] data = data();
+            int from = (int) Math.min(start - 1, data.length);
+            for (int i = from; i + pattern.length <= data.length; i++) {
+                boolean match = true;
+                for (int j = 0; j < pattern.length; j++) {
+                    if (data[i + j] != pattern[j]) {
+                        match = false;
+                        break;
+                    }
+                }
+                if (match) {
+                    return i + 1L;
+                }
+            }
+            return -1;
+        }
+
+        @Override
+        public long position(Blob pattern, long start) throws SQLException {
+            return position(pattern.getBytes(1, (int) pattern.length()), start);
+        }
+
+        @Override
+        public int setBytes(long pos, byte[] bytes) throws SQLException {
+            throw new SQLFeatureNotSupportedException("Blob is read-only");
+        }
+
+        @Override
+        public int setBytes(long pos, byte[] bytes, int offset, int len) throws SQLException {
+            throw new SQLFeatureNotSupportedException("Blob is read-only");
+        }
+
+        @Override
+        public OutputStream setBinaryStream(long pos) throws SQLException {
+            throw new SQLFeatureNotSupportedException("Blob is read-only");
+        }
+
+        @Override
+        public void truncate(long len) throws SQLException {
+            throw new SQLFeatureNotSupportedException("Blob is read-only");
+        }
+
+        @Override
+        public void free() throws SQLException {
+            freed = true;
+            bytes = null;
+        }
+
+        @Override
+        public InputStream getBinaryStream(long pos, long length) throws SQLException {
+            if (length < 0) {
+                throw new SQLException("Invalid length: " + length);
+            }
+            return new ByteArrayInputStream(getBytes(pos, (int) Math.min(length, Integer.MAX_VALUE)));
+        }
+}

libsql-jdbc/src/main/java/com/github/magnusp/libsql/jdbc/LibsqlClob.java

@@ -0,0 +1,114 @@
+package com.github.magnusp.libsql.jdbc;
+
+import java.io.ByteArrayInputStream;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.io.Reader;
+import java.io.StringReader;
+import java.io.Writer;
+import java.nio.charset.StandardCharsets;
+import java.sql.Clob;
+import java.sql.SQLException;
+import java.sql.SQLFeatureNotSupportedException;
+
+    /** Read-only {@link Clob} over the materialized text of one result column. */
+final class LibsqlClob implements Clob {
+
+        private String text;
+        private boolean freed;
+
+        LibsqlClob(String text) {
+            this.text = text;
+        }
+
+        private String data() throws SQLException {
+            if (freed) {
+                throw new SQLException("Clob has been freed");
+            }
+            return text;
+        }
+
+        @Override
+        public long length() throws SQLException {
+            return data().length();
+        }
+
+        @Override
+        public String getSubString(long pos, int length) throws SQLException {
+            String data = data();
+            if (pos < 1) {
+                throw new SQLException("Invalid position: " + pos);
+            }
+            if (length < 0) {
+                throw new SQLException("Invalid length: " + length);
+            }
+            int start = (int) Math.min(pos - 1, data.length());
+            int end = Math.min(start + length, data.length());
+            return data.substring(start, end);
+        }
+
+        @Override
+        public Reader getCharacterStream() throws SQLException {
+            return new StringReader(data());
+        }
+
+        @Override
+        public InputStream getAsciiStream() throws SQLException {
+            return new ByteArrayInputStream(data().getBytes(StandardCharsets.US_ASCII));
+        }
+
+        @Override
+        public long position(String searchstr, long start) throws SQLException {
+            if (start < 1) {
+                throw new SQLException("Invalid position: " + start);
+            }
+            String data = data();
+            int from = (int) Math.min(start - 1, data.length());
+            int index = data.indexOf(searchstr, from);
+            return index < 0 ? -1 : index + 1L;
+        }
+
+        @Override
+        public long position(Clob searchstr, long start) throws SQLException {
+            return position(searchstr.getSubString(1, (int) searchstr.length()), start);
+        }
+
+        @Override
+        public int setString(long pos, String str) throws SQLException {
+            throw new SQLFeatureNotSupportedException("Clob is read-only");
+        }
+
+        @Override
+        public int setString(long pos, String str, int offset, int len) throws SQLException {
+            throw new SQLFeatureNotSupportedException("Clob is read-only");
+        }
+
+        @Override
+        public OutputStream setAsciiStream(long pos) throws SQLException {
+            throw new SQLFeatureNotSupportedException("Clob is read-only");
+        }
+
+        @Override
+        public Writer setCharacterStream(long pos) throws SQLException {
+            throw new SQLFeatureNotSupportedException("Clob is read-only");
+        }
+
+        @Override
+        public void truncate(long len) throws SQLException {
+            throw new SQLFeatureNotSupportedException("Clob is read-only");
+        }
+
+        @Override
+        public void free() throws SQLException {
+            freed = true;
+            text = null;
+        }
+
+        @Override
+        public Reader getCharacterStream(long pos, long length) throws SQLException {
+            if (length < 0) {
+                throw new SQLException("Invalid length: " + length);
+            }
+            return new StringReader(getSubString(pos, (int) Math.min(length, Integer.MAX_VALUE)));
+        }
+}