chore(license): an SPDX header on every source file that had none (LicenseRef-Starship-1.0) [skip ci]

The header scan (Captain Bob, 2026-11-10): 788 source files -- 351 with the
SL-1.0 header, 12 with the old name (docs/working/experiments, kept by
ruling), 31 under someone else's licence (tools/kconfig, Linux's, GPL-2.0:
kept), and 394 with none. Ruled: the SPDX form; capsules (.4th, .f18) and
proofs (.thy) left for a ruling of their own (mkcapsule's 64x16 block format,
content-addressed capsules).

253 files now begin
    SPDX-License-Identifier: LicenseRef-Starship-1.0
    Copyright (c) 2023-2026 Robert A. James
as a /* */ block (C, headers, assembly, linker scripts) or # lines (scripts,
Makefiles, Kconfig; below a shebang or a coding line); tools/mkcapsule.c,
which had the copyright line, gets the SPDX line only.

Not touched: docs/working/ (archive and old campaign material, as the
ruling kept the experiments); v4/system/post_cases.c (generated by
v4/tools/mkpost.py, "do not edit" -- the generator has the header).

Comments only: the kernel builds on amd64, aarch64, riscv64; make -C v4
test-32: 39 programs, 0 failures; every changed script parses.

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

scripts/write_stick.sh

@@ -1,4 +1,6 @@
 #!/usr/bin/env bash
+# SPDX-License-Identifier: LicenseRef-Starship-1.0
+# Copyright (c) 2023-2026 Robert A. James
 # write_stick.sh -- write a StarshipOS stick image to a USB stick, safely, and prove it.
 #
 #   scripts/write_stick.sh IMAGE DEVICE        e.g. build/boards/pc/lithos-pc.img /dev/sdb