fix(v4): the final review's six minors in the ROM boot

- Text after start is refused, as text.c refuses it: before it jumps, the
  ROM reads on to the end of the source; blanks, comments and the ends of
  blobs may follow, a token is ERR-AFTER (26), "text after start".
- A token too long where a name, a target or a value is wanted is "name
  too long", as text.c says: (MISSING) reports "missing" only when no error
  came first.  `", keeps "missing", which is text.c's word for both.
- text.c's "address out of range" names the address, not the value.
- The system's source files are one list, v4/sys_files.h: boot.c, the
  harness and the nucleus test are made from it.
- The ROM's error codes and words are one list, v4/rom_errors.h: boot.c's
  messages, host_map.h's ROM_ERR_* and mkmap's ERR-* are made from it.
- node.h says what v4_node_store does with a ROM address (nothing, as for
  any address outside RAM, D-14); test_host_rom_range pins it.

ROM: 2095 words, rom_hash 0x06d0dcb7a0cb41a1.  dict_hash unchanged,
0xe5a57f3eb72ff94a.  make -C v4 test test-32 hosted-check pass.  QEMU:
amd64, aarch64, riscv64 to ok>, POST 538/538, POST: PASSED.

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

capsules/v4/rom/in.f18

@@ -41,6 +41,13 @@
 \ ( code -- )   stop with an error, noting the line
 : (FAIL)   (FAILED) a! !  (LINE) a! @ (ERRLINE) a! ! ;
 
+\ ( -- )   "missing": a name, a target or a value was wanted and there is
+\ none -- unless an error came first, a token too long or a comment not
+\ closed, which stands, as text.c's first error does
+: (MISSING)
+  (FAILED) a! @ if M  drop ;
+  M: drop  ERR-MISSING jump (FAIL)
+
 \ ( c -- )   one more character of the token: byte (TOKN)+1 of (TOK), into
 \ a cell whose byte there is still zero
 : (PUT)