fix(nas): issued-order PDFs overwrite in place - no more _1 duplicate copies

saveIssuedPdf ran through uniquePath, so whenever two archive calls raced (the fire-and-forget ?save=1 after a save vs. the /file fallback, or two quick saves) the second write landed as <number>_1.pdf - and those copies were invisible to the reader and cleaner (exact-name match), accumulating forever. Now the issued archive writes to the deterministic Vydane/YYYY/MM/<number>.pdf and overwrites (same model as the offers manager), and cleanIssued also sweeps stale <number>_N.pdf duplicates so existing junk self-heals on the next save/delete. Document numbers are digit-only (never contain _), so the suffix match cannot hit a different document. uniquePath remains for received-invoice uploads where name collisions are legitimate.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/__tests__/nas-document-manager.test.ts

@@ -53,4 +53,29 @@ describe("NasDocumentManager issued-PDF round-trip", () => {
       blank.saveIssuedPdf("25P0003", 2026, 6, Buffer.from("x")),
     ).toBeNull();
   });
+
+  it("re-saving the same number OVERWRITES in place — never a _1 duplicate", () => {
+    const first = nas.saveIssuedPdf("25P0004", 2026, 6, Buffer.from("v1"));
+    const second = nas.saveIssuedPdf("25P0004", 2026, 6, Buffer.from("v2"));
+
+    // Same canonical path both times, newest content wins.
+    expect(second).toBe(first);
+    const dir = path.join(tmpBase, "Vydané", "2026", "06");
+    expect(fs.readdirSync(dir)).toEqual(["25P0004.pdf"]);
+    expect(nas.readIssued(second!)!.data.toString()).toBe("v2");
+  });
+
+  it("cleanIssued also sweeps stale _N duplicates left by the old racy save", () => {
+    nas.saveIssuedPdf("25P0005", 2026, 6, Buffer.from("canonical"));
+    // Simulate duplicates the pre-fix uniquePath save created during races.
+    const dir = path.join(tmpBase, "Vydané", "2026", "06");
+    fs.writeFileSync(path.join(dir, "25P0005_1.pdf"), "stale");
+    fs.writeFileSync(path.join(dir, "25P0005_2.pdf"), "stale");
+    // A DIFFERENT number must not be touched by the suffix match.
+    nas.saveIssuedPdf("25P0006", 2026, 6, Buffer.from("other"));
+
+    nas.cleanIssued("25P0005");
+
+    expect(fs.readdirSync(dir).sort()).toEqual(["25P0006.pdf"]);
+  });
 });