Add KiCad module carrier PCB draft

Introduce an editable KiCad 10 schematic and routed two-layer 82 × 80 mm
layout with local provisional footprints, validation tooling, and
component
research. Keep the RS-232 male-module mapping and mechanical clearances
explicitly provisional pending hardware verification.

hardware/PCB/validation/pcb-validation-summary.json

@@ -0,0 +1,47 @@
+{
+  "carrier_bounds_mm": [
+    82,
+    80
+  ],
+  "copper_layers": 2,
+  "draft_thickness_mm": 1.6,
+  "electrical_footprints": 9,
+  "proposed_M3_mounts": 4,
+  "physical_DRC_violations": 0,
+  "unconnected_items": 0,
+  "schematic_pad_nets_match": true,
+  "known_parity_warning": "U2 provisional female-reference footprint assigned on PCB only; schematic footprint intentionally blank",
+  "ignored_DRC_checks": [
+    {
+      "description": "Footprint has no courtyard defined",
+      "key": "missing_courtyard"
+    },
+    {
+      "description": "Track endpoint not centered on via",
+      "key": "track_not_centered_on_via"
+    },
+    {
+      "description": "Tuning profile track geometries",
+      "key": "tuning_profile_track_geometries"
+    },
+    {
+      "description": "Footprint doesn't match symbol's footprint filters",
+      "key": "footprint_filters_mismatch"
+    },
+    {
+      "description": "Footprint component type doesn't match footprint pads",
+      "key": "footprint_type_mismatch"
+    }
+  ],
+  "not_validated": [
+    "male module pin map/fit",
+    "assembly envelope and heights",
+    "header/socket fit",
+    "RF performance and antenna clearance",
+    "power/return-path integrity",
+    "USB power path",
+    "OLED pull-ups",
+    "fabrication process",
+    "hardware operation"
+  ]
+}