fix: use strict ASCII assertion in tests and update OpenAPI spec

Replace fragile Unicode-range regex with positive ASCII check
(/^[\x20-\x7E]+$/) that also catches emoji and supplementary plane
characters. Update OpenAPI spec to document percent-encoding.

apps/api/src/openapi.yaml

@@ -4470,7 +4470,7 @@ paths:
             X-File-Results:
               schema:
                 type: string
-              description: JSON mapping of input index to output filename
+              description: Percent-encoded JSON mapping of input index to output filename (decode with decodeURIComponent before JSON.parse)
           content:
             application/zip:
               schema:

tests/integration/batch.test.ts

@@ -156,7 +156,7 @@ describe("X-File-Results header", () => {
 
     expect(res.statusCode).toBe(200);
     const raw = res.headers["x-file-results"] as string;
-    expect(raw).not.toMatch(/[€-￿]/);
+    expect(raw).toMatch(/^[\x20-\x7E]+$/);
     const fileResults = JSON.parse(decodeURIComponent(raw));
     expect(fileResults["0"]).toContain("图片测试");
     expect(fileResults["1"]).toContain("テスト");
@@ -182,7 +182,7 @@ describe("X-File-Results header", () => {
 
     expect(res.statusCode).toBe(200);
     const raw = res.headers["x-file-results"] as string;
-    expect(raw).not.toMatch(/[€-￿]/);
+    expect(raw).toMatch(/^[\x20-\x7E]+$/);
     const fileResults = JSON.parse(decodeURIComponent(raw));
     expect(fileResults["0"]).toContain("normal");
     expect(fileResults["1"]).toContain("élève");

tests/integration/pipeline-edge-cases.test.ts

@@ -447,7 +447,7 @@ describe("Pipeline batch execution", () => {
 
     expect(res.statusCode).toBe(200);
     const raw = res.headers["x-file-results"] as string;
-    expect(raw).not.toMatch(/[-￿]/);
+    expect(raw).toMatch(/^[\x20-\x7E]+$/);
     const fileResults = JSON.parse(decodeURIComponent(raw));
     expect(fileResults["0"]).toContain("图片");
     expect(fileResults["1"]).toContain("写真テスト");