Fix EXEC/LOAD block-persistence gap and WIREBIND/USE interpreter-race panic (FABRIC-3.md §XII)

Found live while building a cross-ISA FORTH-79 dictionary exerciser:

- capsule_exec_init() zeroed a capsule's block content immediately after
  running it, so LOAD (a genuine FORTH-79 standard word, ACL-allowed even
  for locked identities) could never actually read back what EXEC had
  just written. Removed the clear from capsule_exec_init(); block content
  now persists like any other Standard BLOCK/BUFFER/UPDATE write.
  kernel_main.c's own explicit post-birth clear of Mama's init.4th range
  is untouched.

- USE could redirect the console to a WIREBIND identity's VM before that
  VM's vm_enable_interpreter() step of its own birth sequence had run,
  causing the next typed line to hit vm_assert_interpreter_enabled() and
  panic the entire machine -- not the per-session-recoverable ACL-fault
  path a redirected VM otherwise gets. USE now checks interpreter_enabled
  first and refuses with a retry message instead.

Also includes the amd64/aarch64/riscv64 acceptance boot logs and DoE CSVs
from this session.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EXieurDfDSsDFdnSyusuWo

src/starkernel/capsule/mama_forth_words.c

@@ -483,6 +483,22 @@ void mama_word_use(VM *vm)
         return;
     }
 
+    /* Found live 2026-09-10: WIREBIND announces "attached and ready --
+     * USE it to begin" the moment the target VM is registered, but
+     * vm_enable_interpreter() is a separate, later step of that same
+     * birth sequence. USE redirecting here before that step lands means
+     * the very next line typed hits vm_assert_interpreter_enabled()
+     * inside vm_interpret() and calls host->panic() -- a hard, whole-
+     * machine halt, not the per-session-recoverable fault path the REPL
+     * loop otherwise gives a redirected VM. Refuse the redirect instead;
+     * the caller can just retry USE a moment later once birth finishes. */
+    if (entry.vm_ptr && !((VM *)entry.vm_ptr)->interpreter_enabled) {
+        console_puts("USE: ");
+        console_puts(name_buf);
+        console_println(" not ready yet -- still bootstrapping, try again");
+        return;
+    }
+
     /* BINDSTEP (FABRIC-2.md §F.9/§F.24): if the target has a real
      * installed identity (WIREBIND set this at attach time), re-verify
      * it against whatever drive is CURRENTLY attached -- live, not