Ship Sprint 0 CAD foundations so findings, KiCad hierarchy, BOM match, eval, and optional PCB ingest have a stable contract.

Extend Finding with rule_id/net/pins, flatten multi-sheet .kicad_sch, flag MPN mismatches, score simple_project, and parse .kicad_pcb without running layout DRC.

Co-authored-by: Cursor <cursoragent@cursor.com>

simple_project/eval_golden.json

@@ -0,0 +1,9 @@
+{
+  "required_refs": ["U1", "U2", "U3"],
+  "min_components": 30,
+  "min_nets": 30,
+  "deterministic_keys": [
+    "PS-I2C-001|U3|/I2C0.SDA",
+    "PS-I2C-001|U3|/I2C0.SCL"
+  ]
+}