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_passive_from_value.py

@@ -1,3 +1,4 @@
+from tests.paths import SIMPLE_PROJECT, TAXONOMY
 import asyncio
 from pathlib import Path
 
@@ -57,7 +58,7 @@ def test_resolve_from_value_skips_llm_when_parseable(monkeypatch):
         raise AssertionError("LLM must not run")
 
     monkeypatch.setattr("backend.services.extraction.call_with_fallback", boom)
-    tax = Path(__file__).resolve().parents[1] / "taxonomy"
+    tax = TAXONOMY
     model = asyncio.run(
         resolve_from_value(
             mpn="18pF",
@@ -76,7 +77,7 @@ def test_resolve_from_value_placeholder_no_llm(monkeypatch):
         raise AssertionError("LLM must not run")
 
     monkeypatch.setattr("backend.services.extraction.call_with_fallback", boom)
-    tax = Path(__file__).resolve().parents[1] / "taxonomy"
+    tax = TAXONOMY
     with pytest.raises(ValueError, match="Placeholder"):
         asyncio.run(
             resolve_from_value(