test: cross-read Harbour NTX from Five — 100% binary compatible

Five reads DBF + NTX files created by Harbour:
- NAME index: exact/partial seek, GoTop/Bottom, Skip, SoftSeek
- CITY index: duplicate key seek with correct RecNo order
- ID index: numeric key (Str(ID,6)) seek

17/17 items match Harbour output exactly.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

examples/cross_read_test.prg

@@ -0,0 +1,66 @@
+// Five reads Harbour-created DBF + NTX files
+// Tests binary-level NTX compatibility
+PROCEDURE Main()
+   LOCAL cOut
+
+   cOut := ""
+
+   // Open Harbour-created DBF + NAME index
+   USE "/tmp/cross_test" NEW
+   SET INDEX TO "/tmp/cross_name"
+
+   cOut += "RECORDS=" + LTrim(Str(RecCount()))
+
+   GO TOP
+   cOut += Chr(10) + "N_TOP=" + RTrim(FieldGet(2)) + " " + LTrim(Str(FieldGet(1)))
+
+   SEEK PadR("Name_001", 20)
+   cOut += Chr(10) + "N_S001=" + IIF(Found(),".T.",".F.") + " " + LTrim(Str(RecNo()))
+   SEEK PadR("Name_015", 20)
+   cOut += Chr(10) + "N_S015=" + IIF(Found(),".T.",".F.") + " " + LTrim(Str(RecNo()))
+   SEEK PadR("Name_030", 20)
+   cOut += Chr(10) + "N_S030=" + IIF(Found(),".T.",".F.") + " " + LTrim(Str(RecNo()))
+   SEEK "Name_01"
+   cOut += Chr(10) + "N_P01=" + IIF(Found(),".T.",".F.") + " " + LTrim(Str(RecNo()))
+   SEEK PadR("Name_999", 20)
+   cOut += Chr(10) + "N_MISS=" + IIF(Found(),".T.",".F.") + " " + IIF(EOF(),"EOF",LTrim(Str(RecNo())))
+
+   GO BOTTOM
+   cOut += Chr(10) + "N_BOTTOM=" + RTrim(FieldGet(2)) + " " + LTrim(Str(RecNo()))
+   GO TOP
+   SKIP 4
+   cOut += Chr(10) + "N_SKIP4=" + RTrim(FieldGet(2)) + " " + LTrim(Str(RecNo()))
+
+   SET SOFTSEEK ON
+   SEEK PadR("Name_031", 20)
+   cOut += Chr(10) + "N_SOFT31=" + IIF(Found(),".T.",".F.") + " " + IIF(EOF(),"EOF",LTrim(Str(RecNo())))
+   SET SOFTSEEK OFF
+
+   CLOSE ALL
+
+   // CITY index
+   USE "/tmp/cross_test" NEW
+   SET INDEX TO "/tmp/cross_city"
+
+   GO TOP
+   cOut += Chr(10) + "C_TOP=" + RTrim(FieldGet(3)) + " " + LTrim(Str(FieldGet(1)))
+   SEEK PadR("Seoul", 15)
+   cOut += Chr(10) + "C_SEOUL=" + IIF(Found(),".T.",".F.") + " " + LTrim(Str(RecNo()))
+   SEEK PadR("Tokyo", 15)
+   cOut += Chr(10) + "C_TOKYO=" + IIF(Found(),".T.",".F.") + " " + LTrim(Str(RecNo()))
+   SEEK PadR("NYC", 15)
+   cOut += Chr(10) + "C_NYC=" + IIF(Found(),".T.",".F.") + " " + LTrim(Str(RecNo()))
+   CLOSE ALL
+
+   // ID index
+   USE "/tmp/cross_test" NEW
+   SET INDEX TO "/tmp/cross_id"
+
+   SEEK Str(10, 6)
+   cOut += Chr(10) + "I_S10=" + IIF(Found(),".T.",".F.") + " " + LTrim(Str(RecNo()))
+   SEEK Str(25, 6)
+   cOut += Chr(10) + "I_S25=" + IIF(Found(),".T.",".F.") + " " + LTrim(Str(RecNo()))
+   CLOSE ALL
+
+   ? cOut
+RETURN