Rewrite PADS/BOM dispatch and EDIF ingest as Periscope parsers.

KiCad schematic parser and PCB via≠pad parser stay native. Inherited
parser files remain in dependency/.

tests/test_periscope_parsers_rewrite.py

@@ -0,0 +1,43 @@
+"""Schematic parsers load from src; they do not classify PCB vias as pads."""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+import backend.periscopex.parsers as parsers
+import backend.periscopex.parsers_edif as parsers_edif
+import backend.periscopex.parsers_kicad_pcb as pcb
+from backend.periscopex.parsers import detect_netlist_format, parse_netlist_any
+
+
+def test_schematic_parsers_are_src():
+    for mod, name in ((parsers, "parsers.py"), (parsers_edif, "parsers_edif.py")):
+        path = Path(mod.__file__).resolve()
+        assert path.name == name
+        assert "src" in path.parts
+        assert "Native Periscope overlay" not in path.read_text(encoding="utf-8")[:400]
+
+
+def test_pcb_parser_stays_native_kicad_pcb():
+    path = Path(pcb.__file__).resolve()
+    assert path.parts[-1] == "parsers_kicad_pcb.py"
+    assert "src" in path.parts
+    assert "_is_footprint_via" in path.read_text(encoding="utf-8")
+
+
+def test_detect_format_negative_pcb_is_not_edif_or_kicad_sch():
+    # A board file starts with (kicad_pcb …), not schematic markers.
+    sample = "(kicad_pcb (version 20240108)\n"
+    assert detect_netlist_format(sample) == "pads"  # unknown schematic → PADS sniff default
+
+
+def test_parse_netlist_any_pads_roundtrip(tmp_path: Path):
+    asc = tmp_path / "n.asc"
+    asc.write_text(
+        "*PADS-PCB*\n*PART*\nR1 0603\nU1 QFP48\n*NET*\n*SIGNAL* GND\nR1.1 U1.8\n*SIGNAL* 3V3\nU1.7\n*END*\n"
+    )
+    parts, nets, fmt = parse_netlist_any(asc)
+    assert fmt == "pads"
+    assert parts["R1"] == "0603"
+    assert ("R1", "1") in nets["GND"]
+    assert "GND" in nets