setup-lan-access: Include ~/.ssh/config even if it appears after start

Same rule as c693aa3 (ssh-lan.conf). `Include ~/.ssh/config` went into
~/.ssh-local/config only if ~/.ssh/config was readable at container start.
A file that appeared later, e.g. on a host provisioned after its first
`docker compose up`, was ignored until a restart. Entries ADDED to a file that
already existed were never affected. Measured on tor-ms22 2026-10-19,
expectations written first:
- ssh reads Included files on every connection. A Host added after the config
  was generated resolved with no rerun.
- the bind mount is live: on the Mac, a created file, an atomic replace
  (write + mv) and an append each showed in the container within a second.
So this fixes only the file-appears-later case. The line is now always
written. A file that exists but is unreadable is still left out (ssh would
abort every connection), now with a warning on stderr.

Generated config compared with v1.12.1's: byte-identical when ~/.ssh/config
exists at start (DEVBOX_LAN_ACCESS=jump and auto, with and without
ssh-lan.conf), and stderr is the same too. When the file is absent, the only
difference is the added Include block.
scripts/smoke-test.sh: two new checks, run here the way exec_test runs them
(sh -c). Against v1.12.1, "Included even if created after start" FAILS and
"unreadable left out" PASSES. Against this script both pass, and so do the two
ssh-lan.conf checks.

CHANGELOG Unreleased also names pi-studio v0.10.4 (c83940d), because
check-doc-drift (and so lint on main) had gone red: upstream released 0.10.3
and 0.10.4 right after v1.12.1. 0.10.4 fixes a 0.10.2 Stop regression for
macOS uid -2. Not reachable in the image: 0.10.2's own readStopProcessTable
parsed this container's live ps output (9 rows, min uid 1000). Control: a
macOS-style -2 row throws. The lockfile packages are unchanged, and 0.10.4
loads into pi 1.3.0 with the same 4 studio_* tools, rc 0.

check-doc-drift rc 0, lint-shell rc 0, shellcheck warnings 0 before and after.

rootfs/usr/local/lib/pi-devbox/setup-lan-access.sh

@@ -196,8 +196,17 @@ EOF
   fi
 fi
 
+# Same rule as ssh-lan.conf above: Included even when ~/.ssh/config does not
+# exist yet, so a file that appears after container start (a host provisioned
+# after its first `docker compose up`) is read on the next ssh. Entries added to
+# a file that already existed were always picked up: ssh reads Includes on every
+# connection and the mount is live. Through v1.12.1 the line was written only if
+# the file was readable at start. Only a file that EXISTS but cannot be read is
+# left out, because ssh would then abort every connection, git included.
 INCLUDE_BLOCK=""
-if [ -r "${HOME}/.ssh/config" ]; then
+if [ -e "${HOME}/.ssh/config" ] && [ ! -r "${HOME}/.ssh/config" ]; then
+  echo "setup-lan-access: ${HOME}/.ssh/config exists but is not readable, so it is not Included (ssh would refuse every connection). Fix its permissions, then rerun this script or restart the container." >&2
+else
   INCLUDE_BLOCK=$(cat <<'EOF'
 
 # Your own target hosts. Scope reset to match-all so this Include applies to