feat(v4.0.0): the prompt -- QUIT, ABORT, ABORT" and ."

Layer 5 of the compiler capsule.  The host node is now started at QUIT and
left running: it prompts, reads a line from its console with QUERY,
interprets it, says " ok" or " ERROR", and goes round again.

- capsule/quit.v4: QUIT and ABORT (FORTH-79), ABORT" and (ABORT") as v3 has
  them, ." and (.") (FORTH-79).  Text is compiled as a counted string after
  the call; the run-time word returns to the cell after it.
- INTERPRET prints v3's messages before abandoning a line:
  UNKNOWN WORD: 'xxx' and xxx: compile-only.
- core.v4: CR SPACE COUNT TYPE, as DECOMPOSITION.md gives them.
- input.v4: WORD split so that (PARSE) can take text without skipping
  leading delimiters (." " is an empty string); EXPECT keeps its place in
  memory, so six values may wait on the stack while a line is typed.
- tests/test_host_quit.c: the node is fed characters and its output read;
  16 sessions are transcripts of the v3 binary.

QUIT stops the line from inside any word and says nothing; v3's goes on
with the line and cannot be compiled.  v3's compiled ABORT" crashes.

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

v4/tests/test_host_compile.c

@@ -16,7 +16,8 @@
  *   - ' is FORTH-79's: the parameter field address, and compiled as a
  *     literal inside a definition.  v3's ' parses when the definition runs.
  *   - what is not a word and not a number abandons the line and sets
- *     NODE-ERROR; v3 prints UNKNOWN WORD.  The message comes with QUIT.
+ *     NODE-ERROR, after v3's UNKNOWN WORD message.  What is printed is
+ *     checked in test_host_quit.c, where the node has a console.
  */
 #include "v4/text.h"
 #include "v4/testcode.h"