Split native Periscope (periscope/src) from inherited PinScope (periscope/dependency).

Keep validate.py and the finding engine as-is. AGPL LICENSE stays at the repo root.
Docker overlays dependency then src. Do not delete the inherited tree.

tests/test_pin_mux_check.py

@@ -13,6 +13,8 @@ Locks in:
 
 from __future__ import annotations
 
+from tests.paths import SIMPLE_PROJECT, TAXONOMY
+
 from backend.periscopex.models import (
     Component,
     ComponentConstraints,
@@ -184,7 +186,7 @@ def test_simple_project_uart0_nets_are_feasible_on_mspm0_pins():
     from backend.periscopex.models import DesignGraph
 
     graph = DesignGraph.model_validate_json(
-        (Path(__file__).resolve().parents[1] / "simple_project" / "design_graph.json").read_text()
+        (SIMPLE_PROJECT / "design_graph.json").read_text()
     )
     cmap = {
         "MSPM0G3507SPTR": _constraints(
@@ -206,7 +208,7 @@ def test_simple_project_uart0_swapped_on_mspm0_is_error():
     from backend.periscopex.models import DesignGraph
 
     graph = DesignGraph.model_validate_json(
-        (Path(__file__).resolve().parents[1] / "simple_project" / "design_graph.json").read_text()
+        (SIMPLE_PROJECT / "design_graph.json").read_text()
     )
     cmap = {
         "MSPM0G3507SPTR": _constraints(