feat(log): LOG-FLUSH -- a VM's log records reach Artemis's log ring; and the ring keeps its order when it grows

FABRIC-3 SXXXII.4's deferred LOG-FLUSH, built to the 2026-10-14 rulings
(SXXXVIII): everything a VM logs, at or above the log level, goes into its
own buffer; it goes to Artemis on LOG-FLUSH, when full, and at once on an
ERROR, as one kernel-Hermes LOG_BATCH message she writes on her own turn,
the source being the sender the kernel stamped.  Records that cannot go yet
are counted and reported with the next flush.  LOG-SHOW (Hera only) reads
the ring back -- it had no reader.

Found by the first test that filled it: ring growth overwrote the oldest
record and put blank slots inside the live range.  Fixed test first.

Three ISAs: POST 1052 passed; new parity baseline word_count=526
hash=0x82f4ae7cb2e2d424 (deliberate).  CLAUDE.md: Phase 8 PKI closed.

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

v3/src/word_source/log_words.c

@@ -19,6 +19,7 @@
 #include "starkernel/log_attrib.h"     /* vm_log_attributed_vm() */
 #include "starkernel/capsule_birth.h"  /* capsule_vm_registry_get, VMRegistryEntry */
 #include "starkernel/console.h"        /* console_println() -- (LOG-APPEND-RAW) diagnostics */
+#include "starkernel/vm_log_buffer.h"  /* vm_log_buffer_flush() -- LOG-FLUSH */
 #include <string.h>                    /* strlen */
 #endif
 
@@ -294,6 +295,20 @@ static void log_word_append_raw(VM *vm)
         vm->error = 1;
     }
 }
+
+/* ── LOG-FLUSH ( -- ) ─────────────────────────────────────────────────── */
+/*
+ * Sends this VM's log buffer to Artemis's log ring now, rather than when it
+ * fills or an ERROR record comes (vm_log_buffer.c; FABRIC-3.md SXXXVIII,
+ * 2026-10-14). Records that cannot go yet are counted, and the count goes
+ * with the next flush that can.
+ */
+static void log_word_flush(VM *vm)
+{
+    if (vm_log_buffer_flush(vm) < 0) {
+        console_println("LOG-FLUSH: Artemis not ready -- records counted, sent with the next flush");
+    }
+}
 #endif
 
 /* ── Registration ────────────────────────────────────────────────────── */
@@ -308,6 +323,7 @@ static void log_word_append_raw(VM *vm)
  * String literals:  LOG-ERROR"  LOG-WARN"  LOG-INFO"  LOG-TEST"  LOG-DEBUG"
  * Stack string:     LOG-ERROR-STR  LOG-WARN-STR  LOG-INFO-STR
  *                   LOG-TEST-STR   LOG-DEBUG-STR
+ * Kernel only:      (LOG-APPEND-RAW)  LOG-FLUSH
  */
 void register_log_words(VM *vm)
 {
@@ -344,5 +360,6 @@ void register_log_words(VM *vm)
 
 #ifdef __STARKERNEL__
     register_word(vm, "(LOG-APPEND-RAW)", log_word_append_raw);
+    register_word(vm, "LOG-FLUSH", log_word_flush);
 #endif
 }