feat: convert file manager into a plugin

plugins/file-manager/tests/frontend/sftp-transfer-utils.test.ts

@@ -0,0 +1,27 @@
+import { describe, expect, it } from "vitest";
+import {
+  hasSameHostTransferConflict,
+  joinRemotePath,
+  normalizeRemoteDir,
+} from "../../src/frontend/sftp-transfer-utils";
+
+describe("sftp transfer utilities", () => {
+  it("normalizes and joins remote paths", () => {
+    expect(normalizeRemoteDir(" /home/user// ")).toBe("/home/user");
+    expect(joinRemotePath("/home/user/", "docs/readme.md")).toBe(
+      "/home/user/docs/readme.md",
+    );
+    expect(joinRemotePath("/", "tmp/file.txt")).toBe("/tmp/file.txt");
+    expect(joinRemotePath("home/user", "logs")).toBe("/home/user/logs");
+  });
+
+  it("detects same-host destination conflicts", () => {
+    expect(hasSameHostTransferConflict(["/opt/app"], "/opt/app")).toBe(true);
+    expect(hasSameHostTransferConflict(["/opt/app"], "/opt/app/logs")).toBe(
+      true,
+    );
+    expect(hasSameHostTransferConflict(["/opt/app"], "/opt/releases")).toBe(
+      false,
+    );
+  });
+});