review: iteration-1 fixes across CI, bridge, VM harness, and docs

CI/pipeline:
- KERNEL_TARBALL passed as a YAML env literal '~' was never tilde-expanded
  and would have failed every hosted kernel-build dispatch; the path is now
  exported from the shell. Verified reproducible before the fix.
- Every job gets timeout-minutes; boot smoke uses timeout -k so a wedged
  qemu is SIGKILLed instead of holding the job.
- Tarball fetch + fail-closed sha256 verification deduplicated into
  build/fetch-kernel-tarball.sh (with curl retries), used by build-kernel.sh
  and both CI jobs. busybox fetch gains retries too.
- ccache layer for kernel-build (cache keyed on defconfig+patches) recovers
  the incremental-compile speed the ephemeral-runner move cost.
- build-kernel.sh now asserts every fragment option survived olddefconfig —
  merge_config -m pastes text and Kconfig silently drops unmet symbols.

rs485-bridge:
- pending-buffer cap (2x max RTU ADU) instead of unbounded growth;
  explicit accept-loop error handling with backoff instead of .flatten();
  per-arm inline bounds instead of the string-keyed lookup whose default
  would have mis-bounded a future get-input; control-socket cleanup errors
  surfaced; flag-shaped values rejected in arg parsing; doc example uses a
  private mktemp dir. Test timing margins widened for contended runners
  (gap 25->120ms, 60x margin on the split-frame test).

VM harness:
- stage-1/stage-2 boot scripts share one validated slot parser and one
  by-name populator (qemu/rootfs/etc/warden-lib.sh) — the duplicated
  parser had already diverged on validation; userdata/oem mount failures
  now fail fast with a greppable sentinel; udhcpc fallback keys off the
  interface actually having an address; switch_root applet guarded.
- boot-smoke delegates the qemu invocation to run.sh (machine shape lives
  in ONE place); run.sh port 0 disables a hostfwd.
- mkimage: unknown partition names fail at build time; DISK_END is a max,
  not last-entry; --state keys validated as filenames.
- portal-scenario: mock readiness is asserted (no silent fall-through),
  hostfwd port collisions retried, mount-failure sentinel fails fast.
- ui-shot: fixed sleeps replaced with bounded screendump polling; the
  repaint assertion is real and documented as such. qmp.py loses its
  module-global and gains argv validation.

Docs/scrub: bench-host paths and the site AP name removed from six more
port docs and two evidence tables; path-bearing build artifacts (.elf,
.map) untracked (the 154-byte firmware .bin is path-free and stays);
ADR-0003 marked visibility-superseded by ADR-0007; stale section
cross-reference fixed; flare-edge noted as private for outside readers;
stale root-level review report removed per the new workspace rule.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018HUayid7W5w7jBdb9Rrj1K

qemu/tests/boot-smoke.sh

@@ -27,13 +27,15 @@ command -v qemu-system-arm >/dev/null || {
 LOG="$(mktemp "${TMPDIR:-/tmp}/warden-qemu-smoke.XXXXXX")"
 trap 'rm -f "$LOG"' EXIT
 
-# NOTE: never pass `earlyprintk` — the config's DEBUG_UART_PHYS is the RV1106's
-# 0xff4c0000, which does not exist on -M virt.
-timeout 180 qemu-system-arm \
-  -M virt,highmem=off -cpu cortex-a7 -smp 1 -m 256M \
-  -kernel "$ZIMAGE" -initrd "$INITRD" \
-  -append "console=ttyAMA0 rdinit=/init" \
-  -nographic -no-reboot </dev/null | tee "$LOG" || {
+# Delegate the qemu invocation to run.sh (--no-disk) so the machine shape
+# (-M virt,highmem=off, cpu, memory, virtio topology) lives in exactly one
+# place — the two hand-copied invocations had already drifted once.
+# timeout -k: a wedged qemu that ignores SIGTERM gets SIGKILLed 10s later
+# instead of holding the job until the workflow-level timeout.
+timeout -k 10 180 bash "$QDIR/run.sh" \
+  --kernel "$ZIMAGE" --initrd "$INITRD" --no-disk \
+  --ssh-port 0 --http-port 0 --api-port 0 \
+  </dev/null | tee "$LOG" || {
     echo "FATAL: qemu exited non-zero (or hung until the 180s timeout)" >&2
     exit 1
   }