Add REVIEW.md: complete hardware-review coverage record

Documents everything examined in the 2026-07-17/18 review - not just
findings but full coverage with verdicts, so future sessions know what
not to re-review: per-sheet verification against datasheets and the
WIZnet reference design, the settled look-wrong-but-correct list
(VPHY/VPLL on 3.3V, D4/D5 floating VBUS + flow-through, EN at 12V,
RSET 12.4k, no CT cap, DO/DI direction evidence), PCB/JLC/BOM audit
state, explicit not-reviewed list (bench/gateware items), and a binding
rule to keep the file updated in the same commit as any change to a
reviewed circuit. Referenced from CLAUDE.md alongside TODO.md.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

hardware/re-bba-rb/re-bba-rb.kicad_prl

@@ -1,6 +1,6 @@
 {
   "board": {
-    "active_layer": 0,
+    "active_layer": 2,
     "active_layer_preset": "",
     "auto_track_width": true,
     "hidden_netclasses": [],