wip(build): acceptance boots a fresh data stick -- every run is a first boot (#92, Task 3) [skip ci]

Not yet accepted (plan 2026-10-29-stick-5, Task 3).
- kernel/Makefile: a v4 `qemu` boot attaches a fresh data stick
  (DATASTICK=1) and nothing else; ARTDISK/ZUSEDISK keep the minted pair only
  for system=v3 (QEMU_V3_BOOT, from KERNEL_ARGS).
- qemu_session.py: the Makefile's defaults for every mode but those that ask
  for the pair by name (stick_artemis, two_sticks, artemis_unsigned,
  raw_ident, v3_keys) or for no drive; `zuse` now expects the genesis line.
- nightly.sh: accept stick-high runs stick_genesis (the stick as built).
- .claude/CLAUDE.md "The disks", the stick-high line; disk/README.md (the
  pair: tests and v3 only); STICK.md 11, increments 3 and 5 done.

Before the change: zuse on amd64 FAIL -- the pair's "identity confirmed",
no genesis line (logs/20261108-130732).

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

disk/README.md

@@ -168,7 +168,14 @@ carrying timestamp noise in git history.
   image's bytes, each exactly its file's size), fresh before every boot, and
   that is `ZUSEDISK`'s default; `make boot_image TARGET=PC
   STICK_PAIR=disk/zuse-scratch` puts the pair in the PC stick the same way.
-  The files here are unchanged. Increment 5 retires the pair.
+  The files here are unchanged.
+
+  **For tests and v3 only (2026-11-08, plan 2026-10-29-stick-5, Task 3):** a
+  v4 `qemu` boot no longer attaches the pair; it attaches a fresh data stick,
+  whose first boot mints its own Zuse. The pair stays for the tests that ask
+  for a known Zuse by name (`scripts/qemu_session.py`'s `stick_zuse`,
+  `two_sticks`, `stick_artemis`, `raw_ident`, `v3_keys`, the hot-plug and GPT
+  modes) and as the defaults of a `system=v3` boot.
 
 - **The StarshipOS stick and data stick are not here** (2026-10-27,
   `docs/v4.0.0/STICK.md` §4, §9): they are build output, made fresh by