feat(v4.0.0): CASE, ['], S", WORDS, FORGET and FENCE

- compile.v4: CASE OF ENDOF ENDCASE, as v3 (they nest; a word out of
  place is a control structure mismatch); ['] and [LITERAL].
- quit.v4: S" and its run-time word; at the prompt the text is copied to
  PAD.
- capsule/system.v4: WORDS and VLIST; FORGET (FORTH-79), which gives the
  space back and will not remove a word below FENCE -- the capsule's own
  words -- where v3's FORGET DUP succeeds.
- tests/test_host_quit.c: ten more transcripts of the v3 binary, and
  nesting, the fence and the listing.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

v4/tests/host_map.h

@@ -40,6 +40,7 @@
 #define FVARS        (TOP - 105)                /* (F): forth.v4, 7 cells */
 #define SVARS        (TOP - 540 - (v4_cell)V4_DATA_DEPTH)   /* (S): where PICK and ROLL set stack values aside, one cell for each cell of the stack */
 #define WVARS        (TOP - 99)                 /* (W): numout.v4, 3 cells */
+#define FENCE        (TOP - 26)                 /* FORGET's lower limit */
 #define HLD          (TOP - 25)                 /* where the pictured number has got to */
 #define QVARS        (TOP - 52)                 /* (Q): quit.v4, 2 cells */
 
@@ -116,6 +117,7 @@ static int host_load(v4_text *tx, v4_node *n, const char *const *files, unsigned
     v4_text_constant(tx, "(X)", XVARS);
     v4_text_constant(tx, "MAX-INT", (v4_cell)(V4_MSB - 1u));
     v4_text_constant(tx, "HLD", HLD);
+    v4_text_constant(tx, "FENCE", FENCE);
     v4_text_constant(tx, "HEND", HEND);
     v4_text_constant(tx, "-HFLOOR", -(HEND - 62));
     v4_text_constant(tx, "DSTACK-DEPTH", DSTACK_REG);