fix: put-backs no longer name the untracked version.h (#145)

90c5c140 untracked v3/include/version.h, but six places still put it back
with git checkout. Git refuses the whole checkout when one path is unknown:

- scripts/nightly.sh images (set -e): the stage ended there, so the nightly
  (images, publish, proofs) and release.yml (images, docs, gitea-release)
  would fail. Acceptance does not run images, so it passed.
- scripts/check_images.sh (no -e), demo/build-iso.sh, demo/mint-zuse.sh
  (|| true): silently put nothing back, BLOCK_MAP.md and the SBOM included.
- scripts/qemu_session.py: an error after every boot, otherwise harmless.
- boards/BRINGUP.md: the step said to put it back.

BLOCK_MAP.md stays in every put-back: a signed build (CI's) still rewrites
its Signed column. Found while setting up alpha.5; Captain Bob: fix it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017RzZgrf7V7Zk2iczBXDRbm

scripts/qemu_session.py

@@ -1125,6 +1125,6 @@ else:
 print(f"RESULT: {'PASS' if ok else 'FAIL'}", flush=True)
 if not globals().get("boot_done"):
     shutdown()
-for f in ("v3/include/version.h", "capsules/BLOCK_MAP.md"):
+for f in ("capsules/BLOCK_MAP.md",):          # a signed build rewrites its Signed column; version.h is untracked (#145)
     subprocess.run(["git", "checkout", "-q", "--", f], cwd=ROOT)
 sys.exit(0 if ok else 2)