feat(rtl): LIST/DISPLAY TO FILE — text output redirection

Wire up TO FILE for both LIST and DISPLAY: __dbList grows a 9th
parameter cFile, opens it (truncating any prior content) when non-
empty, and writes the formatted rows there via fmt.Fprintln. Default
behavior (no TO FILE) still goes to stdout.

std.ch gets two new rules placed *before* the regular LIST/DISPLAY
patterns so they win when TO FILE is present:

  LIST    [<v,...>] TO FILE <(f)> [OFF] [FOR] [WHILE] [NEXT] ...
  DISPLAY [<v,...>] TO FILE <(f)> [OFF] [FOR] [WHILE] [NEXT] ...

Open failure raises a clear *HbError ("LIST/DISPLAY TO FILE: cannot
create <path> — <syscall reason>") so callers know exactly what went
wrong instead of getting partial-or-empty output.

TO PRINTER stays rejected via __dbNotImpl — Five doesn't drive a
printer port. Test coverage: tests/std_ch/test_list_to_file.prg
exercises four shapes (full LIST, single-row DISPLAY, OFF + FOR with
explicit fields, and confirms TO PRINTER still raises). Wired into
the std.ch runner so the regression suite now stands at 14/14.

Gates green:
  go test ./...      : PASS
  FiveSql2 SQL:1999  : 43/43
  Harbour compat     : 56/56
  std.ch suite       : 14/14

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/std_ch/run.sh

@@ -23,6 +23,7 @@ TESTS=(
    test_copy
    test_sort
    test_list
+   test_list_to_file
    test_total
    test_join
    test_update

tests/std_ch/test_list_to_file.prg

@@ -0,0 +1,73 @@
+/* LIST / DISPLAY TO FILE — text output redirected to a file. */
+
+PROCEDURE Main()
+   LOCAL aStruct, cBuf, e
+
+   FErase("p.dbf")
+   FErase("out.txt")
+
+   aStruct := { ;
+      { "ID",   "N",  4, 0 }, ;
+      { "NAME", "C", 10, 0 }, ;
+      { "AGE",  "N",  3, 0 } }
+   dbCreate("p.dbf", aStruct)
+   USE p.dbf NEW EXCLUSIVE ALIAS p
+   dbAppend(); FieldPut(1,1); FieldPut(2,"Alice"); FieldPut(3,18)
+   dbAppend(); FieldPut(1,2); FieldPut(2,"Bob");   FieldPut(3,25)
+   dbAppend(); FieldPut(1,3); FieldPut(2,"Carol"); FieldPut(3,30)
+   dbCommit()
+
+   /* 1. LIST TO FILE  — full table */
+   dbGoTop()
+   LIST TO FILE out.txt
+
+   cBuf := MemoRead("out.txt")
+   ? "1. file size:", Len(cBuf), "bytes (expect > 0)"
+   IF Len(cBuf) == 0
+      ? "FAIL: empty output file"
+      RETURN
+   ENDIF
+   ? "1. file content:"
+   ? cBuf
+
+   /* 2. DISPLAY TO FILE — single record */
+   FErase("out.txt")
+   dbGoto(2)
+   DISPLAY TO FILE out.txt
+
+   cBuf := MemoRead("out.txt")
+   ? "2. DISPLAY single-row file:"
+   ? cBuf
+   IF !("Bob" $ cBuf)
+      ? "FAIL: Bob row missing"
+      RETURN
+   ENDIF
+
+   /* 3. LIST TO FILE with OFF + FOR — std.ch pattern order is
+      `[<off:OFF>] [FOR <for>]`, same as Harbour. */
+   FErase("out.txt")
+   dbGoTop()
+   LIST p->id, p->name TO FILE out.txt OFF FOR p->age >= 25
+
+   cBuf := MemoRead("out.txt")
+   ? "3. selective+OFF file:"
+   ? cBuf
+   IF "Alice" $ cBuf
+      ? "FAIL: Alice (age 18) shouldn't be in FOR age>=25 output"
+      RETURN
+   ENDIF
+
+   /* 4. TO PRINTER — should still reject */
+   e := .F.
+   BEGIN SEQUENCE
+      LIST TO PRINTER
+   RECOVER
+      e := .T.
+   END SEQUENCE
+   ? "4. TO PRINTER rejected:", e, "(expect .T.)"
+
+   dbCloseArea()
+   FErase("p.dbf")
+   FErase("out.txt")
+   ? "DONE"
+   RETURN