Advance PCB carrier to A1 layout

Reposition the ESP32 and RS-232 reference within the notched outline,
preserve the A0 snapshot, and add second-pass two-layer routing
evidence.
Refresh validation reports and draft previews while keeping fabrication
status provisional.

hardware/PCB/validation/pcb-routing-preservation.json

@@ -0,0 +1,27 @@
+{
+  "a0_snapshot_unchanged": true,
+  "a1_unrouted_snapshot_unchanged": true,
+  "protected_files_unchanged": [
+    "serial-carrier.kicad_pro",
+    "serial-carrier.kicad_sch",
+    "serial-carrier.kicad_prl",
+    "fp-lib-table",
+    "sym-lib-table",
+    "Carrier.kicad_sym",
+    "Carrier.pretty/OLED_26mm_I2C_Provisional.kicad_mod",
+    "Carrier.pretty/HW678_2x22_Provisional.kicad_mod",
+    "Carrier.pretty/MAX3243_Reference_Provisional.kicad_mod"
+  ],
+  "intentional_documentation_updates": [
+    "README.md",
+    "pcb-draft-notes.md"
+  ],
+  "cad_projection_graphics": 7,
+  "footprints_identical_except_authorized_placement": true,
+  "footprint_count": 13,
+  "unrelated_board_graphics_preserved": 5,
+  "non_owned_board_graphic_uuids_preserved": true,
+  "refreshed_device_silkscreen_items": 91,
+  "pcb_editor_lock_absent": true,
+  "final_board_sha256": "53e36538c0669604457b9e1a9ff1b1e20422970e8f9f356088c4581868ad5045"
+}