Don't strip trailing null byte from binary records in Altium parser

ReadProperties() unconditionally stripped a trailing 0x00 byte from all
records. This is correct for text records where 0x00 is a string
terminator, but binary records contain raw compressed data where 0x00 is
valid payload. When a zlib stream happened to end with 0x00, stripping
it caused ReadFullPascalString() to throw out_of_range, crashing Altium
.SchLib imports.

Only strip the null byte for non-binary records.

Fixes https://gitlab.com/kicad/code/kicad/-/issues/23013

common/io/altium/altium_binary_parser.cpp

@@ -382,7 +382,7 @@ std::map<wxString, wxString> ALTIUM_BINARY_PARSER::ReadProperties(
 
     // we use std::string because std::string can handle NULL-bytes
     // wxString would end the string at the first NULL-byte
-    std::string str = std::string( m_pos, length - ( hasNullByte ? 1 : 0 ) );
+    std::string str = std::string( m_pos, length - ( ( hasNullByte && !isBinary ) ? 1 : 0 ) );
     m_pos += length;
 
     if( isBinary )

qa/tests/common/io/altium/test_altium_parser.cpp

@@ -286,4 +286,40 @@ BOOST_DATA_TEST_CASE( ReadProperties,
 }
 
 
+/**
+ * Verify that binary records ending with 0x00 are not truncated.
+ * Regression test for https://gitlab.com/kicad/code/kicad/-/issues/23013
+ */
+BOOST_AUTO_TEST_CASE( ReadPropertiesBinaryNullBytePreserved )
+{
+    // Simulate a binary record whose payload ends with 0x00.
+    // The MSB of the 4-byte length field flags the record as binary.
+    const char binaryPayload[] = { 0x01, 0x02, 0x03, 0x00 };
+    const uint32_t payloadLen = sizeof( binaryPayload );
+    const uint32_t lengthField = payloadLen | 0x01000000;
+
+    size_t                  totalSize = 4 + payloadLen;
+    std::unique_ptr<char[]> content = std::make_unique<char[]>( totalSize );
+
+    std::memcpy( content.get(), &lengthField, 4 );
+    std::memcpy( content.get() + 4, binaryPayload, payloadLen );
+
+    ALTIUM_BINARY_PARSER parser( content, totalSize );
+
+    std::string receivedData;
+    auto binaryHandler = [&]( const std::string& aData ) -> std::map<wxString, wxString>
+    {
+        receivedData = aData;
+        return {};
+    };
+
+    parser.ReadProperties( binaryHandler );
+
+    BOOST_CHECK_EQUAL( parser.HasParsingError(), false );
+    BOOST_CHECK_EQUAL( parser.GetRemainingBytes(), 0 );
+    BOOST_CHECK_EQUAL( receivedData.size(), payloadLen );
+    BOOST_CHECK_EQUAL( receivedData.back(), '\0' );
+}
+
+
 BOOST_AUTO_TEST_SUITE_END()