chore(confidence-engine): upgrade to zod 4

tests/reconstruction.test.js

@@ -36,7 +36,8 @@ describe("reconstruction schema", () => {
     const result = reconstructionSchema.safeParse(input);
     expect(result.success).toBe(false);
     if (!result.success) {
-      expect(result.error.issues[0].message).toContain("Expected");
+      expect(result.error.issues.length).toBeGreaterThan(0);
+      expect(result.error.issues[0].path).toContain("confidence");
     }
   });
 

tests/reconstruction/compatibility.test.js

@@ -254,10 +254,10 @@ describe("analyseScenario compatibility", () => {
     expect(result.validationIssues).toContainEqual(expect.objectContaining({
       path: ["reconstruction", "observedStates", 0, "description"],
       code: "invalid_type",
-      message: "Required",
+      expected: "string",
     }));
     expect(result.providerApiPath).toBe("/api/chat");
-    expect(result.errors).toContain("reconstruction: Required");
+    expect(result.errors).toContainEqual(expect.stringMatching(/^reconstruction:/));
   });
 
   it("succeeds when reported_claim is the only evidenceType mismatch", async () => {