feat(kernel): sk_v4_mint_zuse -- the real Zuse minted onto a second stick, read back before the marker names her (#92, 4.5) [skip ci]

Asks for a stick, shows its size, writes nothing until YES; then gpt_write_one, the partition's first devblocks zeroed, a fresh Zuse minted, read back, and only then the marker's real key. Any failure before the marker: 'failed -- nothing changed'. The gate remembers the last stick it turned away as a spare, offered first by the next mint. Builds on three ISAs; not yet called.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GE3SDvQn5EoxdGufk84zz2

kernel/include/starkernel/v4/sk_v4_identity.h

@@ -9,6 +9,7 @@
 
 #include "uefi.h"   /* BootDisk */
 #include "blkio.h"
+#include "starkernel/v4/sk_v4_marker.h"
 
 /* After POST and the block chain: every xHCI controller brought up, and the
  * heartbeat started, as the v3 path does before its headless wait. `boot_disk`
@@ -38,6 +39,16 @@ void sk_v4_identity_check_now(void);
  * leaves: 0. */
 int sk_v4_identity_offer_wait(blkio_dev_t **raw, uint64_t *bytes);
 
+/* For the mint: the system stick's Artemis is attached; the offered stick is
+ * still plugged in; the offered stick handed back unused (a mint refused or
+ * stopped -- the next mint offers it again); the genesis marker as read, and
+ * as the mint has just written it. */
+int  sk_v4_identity_stick_in(void);
+int  sk_v4_identity_offered_present(void);
+void sk_v4_identity_release_offered(void);
+const sk_v4_marker_t *sk_v4_identity_marker(void);
+void sk_v4_identity_set_marker(const sk_v4_marker_t *m);
+
 /* The arrival check run again on the offered stick, now that the mint has
  * written its GPT and identity (it is then recognised as the real Zuse's). */
 void sk_v4_identity_recheck_offered(void);

kernel/include/starkernel/v4/sk_v4_mint.h

@@ -0,0 +1,16 @@
+/* sk_v4_mint.h -- MINT-ZUSE: the real Zuse minted onto a second stick
+ * (docs/v4.0.0/STICK.md 6a; plan 2026-10-29-stick-5, Task 4).
+ *
+ * Built only with STARFORTH_V4=1 (Kconfig.kernel).
+ */
+#ifndef STARKERNEL_V4_SK_V4_MINT_H
+#define STARKERNEL_V4_SK_V4_MINT_H
+
+/* The whole of STICK.md 6a's minting: asks for a stick, shows its size, writes
+ * nothing until YES, then a GPT and a fresh Zuse identity on it, read back,
+ * and only then the real key in the genesis marker. 0 when she is minted;
+ * -1 otherwise, with its line said and the marker as it was. Run by the
+ * MINT-ZUSE word, and (Task 5) the fixed screen's R. */
+int sk_v4_mint_zuse(void);
+
+#endif /* STARKERNEL_V4_SK_V4_MINT_H */