review: fix review findings (correctness, hardening, doc-accuracy)

First recursive code-review-harness pass over the authored SDK code (sim/,
config-lint, flowgen, drivers/{relays,freshness}, build/, ci.yml). Four parallel
dimension reviewers; all findings at every severity corrected per workspace rule.

Correctness / reliability:
- freshness.c min_budget_ms: use a `seen` flag, not `best==0`, as the empty
  sentinel — a zero-tolerance (max_stale_ms==0) binding was silently widened to a
  looser neighbour's budget. Regression test added; still 66/66 MC/DC.
- config-lint parse_reserved_ranges: match `reg` as a whole property token (ident
  boundary before, `=` after) so `reg-names` / a `region-*` label no longer
  mis-parses into a bogus reserved range.
- config-lint loader check: fail closed — flag any loader with a LOAD_ADDR that is
  not a known-safe boot component, instead of only known MCU names, so a future
  coprocessor ("Rtos"/"Bl32") can't slip past the 0x40000-brick gate.
- build-kernel.sh: sha256 verification is now mandatory (refuse to build if the pin
  is missing) and the mktemp scratch tree is removed on exit (trap), while a
  caller-provided WORK is left intact for CI artifact upload.

Test quality:
- freshness: added the age==max_stale boundary case and a clock-wraparound
  (now < last_ok) fail-safe-to-UNKNOWN test.
- relays: unsetenv(WARDEN_GPIO_ROOT) at main() so the NULL-env arm is hermetic.

Security / CI:
- ci.yml: top-level `permissions: contents: read` (badges overrides to write);
  pin taiki-e/install-action to commit SHA (v2.86.7).

Maintainability / docs:
- drivers/enforce-mcdc.sh: one shared, name-derived gate replaces the two
  copy-pasted per-driver scripts; Makefiles call ../../enforce-mcdc.sh.
- docs/architecture.md: §3/§4/§6/§7 rewritten to match reality — NPU/RGA models,
  config-lint, and the relays+freshness MC/DC harnesses are done; kernel §6 now
  reflects the 5.10->6.18.46 forward-port (ADR-0001), not the superseded plan44/6.6.
- README: status blurb + layout table corrected (kernel/, .github/; stale ci/ and
  patches/ descriptions fixed). hpmcu "8 tests" -> 7 in docs.
- freshness.{c,h}: ADR reference points at flare-edge ADR-0004 (warden-sdk's
  ADR-0004 is the CI runner — number collision).
- normalize rustfmt drift across sim/ + config-lint.

All green: sim 37 tests, config-lint 8 tests, both drivers 100% MC/DC (relays
40/40, freshness 66/66), clippy clean under -D warnings, gitleaks clean.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017wB8KB3MMQztRDXCMCkPrf

drivers/README.md

@@ -17,8 +17,11 @@ Self-contained logic with a clean seam, measured to **100% MC/DC** (gcc-14
 
 **Adding a Tier-1 driver:** copy `<name>.{c,h}` here, put the hardware/OS calls behind
 a small injectable seam, then mirror `relays/test/` (a fake backend for the logic
-branches + a real backend over a scratch tree for the plumbing) and
-`enforce-mcdc.sh`. The CI job picks up any `drivers/*/test/Makefile` automatically.
+branches + a real backend over a scratch tree for the plumbing). Reuse the shared
+gate — the Makefile calls `bash ../../enforce-mcdc.sh <gcov.log> build/<name>.c.gcov
+build/test.rc` (it derives the driver name from the `.gcov` file, so there is no
+per-driver copy to keep in sync). The CI `mcdc` job picks up any
+`drivers/*/test/Makefile` automatically.
 
 ## Tier 2 — serious testing + fault-injection + benchmarks
 
@@ -30,7 +33,7 @@ is already modelled and tested here** in `../sim/`:
 |---|---|---|
 | `modbus_engine.c` (RS485 master) | 11 pty scenarios + fault-injection + a compiled corpus walk (flare-edge `tools/modbus-sim/`, green) | `sim::modbus` RTU slave (11 tests, silent-drop/forced-NAK faults) + `modbus_read_holding` benchmark |
 | `warden_rga.c` (RGA offload) | offload-dispatch + CPU-fallback logic | `sim::rga` recording `improcess` fake (programmable IM_STATUS) + `rga_improcess` benchmark |
-| HPMCU supervisor (`hpmcu.rs`) | arm/beat/fire + boot-grace safety property | `sim::hpmcu` (8 tests) + `hpmcu_tick` benchmark |
+| HPMCU supervisor (`hpmcu.rs`) | arm/beat/fire + boot-grace safety property | `sim::hpmcu` (7 tests) + `hpmcu_tick` benchmark |
 
 **Why the Tier-2 *source* isn't vendored here yet:** `modbus_engine.c` and
 `warden_rga.c` pull in shared UI headers (`platform.h`, `settings.h`, `lv_*`) and