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

boards/BRINGUP.md

@@ -144,8 +144,8 @@ make boot_image TARGET=MILKV  EMERGENCY_CONSOLE_ENABLED=1
       thumbdrive attached. After a clean build it does (tried on `MILKV`).
 - [ ] The Pi 5 build fetches the board's DTB once from the pinned firmware release; with no
       network, pass `RPI5_DTB=/path/to/bcm2712-rpi-5-b.dtb`.
-- [ ] Put back `v3/include/version.h` and `capsules/BLOCK_MAP.md` afterwards: the build
-      rewrites both.
+- [ ] Put back `capsules/BLOCK_MAP.md` afterwards if the build was signed: a signed build rewrites
+      its Signed column. (`v3/include/version.h` is untracked since 2026-11-11, #145.)
 
 ### 3.2 Rehearse each image as its own disk