fix(python): preserve historical signed code fields

Keep signed co_stacksize and co_flags for historical magic entries whose constructors accepted them. Preserve magic 3410 with a constructor-revision limitation; reject negative values from 3411 onward.

Fixes #6487

src/domain/python/pythonPyc.test.ts

@@ -10,6 +10,7 @@ it("maps pinned CPython 3.7–3.13 magics and leaves gaps unknown", () => {
     python_version: "3.7",
     code_layout: "py37",
     header_bytes: 16,
+    negative_code_fields: "accepted",
   });
   expect(pythonPycMagicEntry(3390)).toMatchObject({
     python_version: "3.7",
@@ -23,16 +24,24 @@ it("maps pinned CPython 3.7–3.13 magics and leaves gaps unknown", () => {
     python_version: "3.8",
     code_layout: "py38",
     header_bytes: 16,
+    negative_code_fields: "rejected",
   });
+  expect(pythonPycMagicEntry(3401)?.negative_code_fields).toBe("accepted");
+  expect(pythonPycMagicEntry(3410)?.negative_code_fields).toBe(
+    "revision-dependent",
+  );
+  expect(pythonPycMagicEntry(3411)?.negative_code_fields).toBe("rejected");
   expect(pythonPycMagicEntry(3531)).toEqual({
     python_version: "3.12",
     code_layout: "py311",
     header_bytes: 16,
+    negative_code_fields: "rejected",
   });
   expect(pythonPycMagicEntry(3571)).toEqual({
     python_version: "3.13",
     code_layout: "py311",
     header_bytes: 16,
+    negative_code_fields: "rejected",
   });
   expect(pythonPycMagicEntry(3450)).toBeNull();
   expect(pythonPycMagicEntry(62171)).toBeNull();