Remove dead TYPE_MASK and TYPE_NULLABLE_FLAG

The nullable-flag-in-type-code mechanism was replaced by inline
null count encoding. Since the protocol was never released, remove
the dead constants and their tests entirely rather than
deprecating them.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: mtopolnik

core/src/main/java/io/questdb/client/cutlass/qwp/protocol/QwpConstants.java

@@ -209,14 +209,6 @@ public final class QwpConstants {
      * Wire format: [nDims (1B)] [dim1_len (4B)]...[dimN_len (4B)] [flattened values (LE)]
      */
     public static final byte TYPE_LONG_ARRAY = 0x12;
-    /**
-     * Mask for type code without nullable flag.
-     */
-    public static final byte TYPE_MASK = 0x7F;
-    /**
-     * High bit indicating nullable column.
-     */
-    public static final byte TYPE_NULLABLE_FLAG = (byte) 0x80;
     /**
      * Column type: SHORT (int16, little-endian).
      */

core/src/test/java/io/questdb/client/test/cutlass/qwp/protocol/QwpConstantsTest.java

@@ -172,16 +172,6 @@ public void testMagicBytesValue() {
         Assert.assertEquals((byte) ((MAGIC_MESSAGE >> 24) & 0xFF), expected[3]);
     }
 
-    @Test
-    public void testNullableFlag() {
-        Assert.assertEquals((byte) 0x80, TYPE_NULLABLE_FLAG);
-        Assert.assertEquals(0x7F, TYPE_MASK);
-
-        // Test nullable type extraction
-        byte nullableInt = (byte) (TYPE_INT | TYPE_NULLABLE_FLAG);
-        Assert.assertEquals(TYPE_INT, nullableInt & TYPE_MASK);
-    }
-
     @Test
     public void testSchemaModes() {
         Assert.assertEquals(0x00, SCHEMA_MODE_FULL);