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>

tests/test_passive_rail_check.py

@@ -104,6 +104,8 @@ def test_i2c_missing_pullup():
     findings = check_i2c_pullups(g, cons)
     assert len(findings) == 1
     assert findings[0].source == "i2c_pullup_check"
+    assert findings[0].rule_id == "PS-I2C-001"
+    assert findings[0].net == "I2C_SDA"
 
 
 def test_i2c_pullup_present():