feat(files): add save-as-new vs overwrite choice for library file edits (#564)

Editing a file from the library used to silently supersede it: the worker auto-saved every result as a new version and the leaf-only listing hid the original, which read as a destructive overwrite. Tool pages now show a per-edit choice for library-sourced files. The default saves the result as an independent new file and keeps the original; picking overwrite keeps the old superseding-version behavior.

The client sends a saveMode multipart field next to fileId, validated with a 400 on unknown values, and autoSaveToLibrary branches on it. Every hand-written route that honors fileId parses the field the same way as the factory. The review panel shows where an auto-saved result went instead of offering a second, duplicate save. Tools whose route or submitter ignores fileId keep the selector hidden via a shared unsupported-tools set, and the choice resets to the non-destructive default whenever a new file is staged.

Closes #495

tests/unit/web/review-panel-saved-state.test.tsx

@@ -0,0 +1,61 @@
+// @vitest-environment jsdom
+import { cleanup, render, screen } from "@testing-library/react";
+import { MemoryRouter } from "react-router-dom";
+import { afterEach, describe, expect, it, vi } from "vitest";
+
+vi.mock("@/lib/analytics", () => ({
+  track: vi.fn(),
+}));
+
+vi.mock("@/components/feedback/tool-feedback-prompt", () => ({
+  ToolFeedbackPrompt: () => null,
+}));
+
+import { ReviewPanel } from "@/components/common/review-panel";
+
+function renderPanel(props: Partial<Parameters<typeof ReviewPanel>[0]> = {}) {
+  return render(
+    <MemoryRouter>
+      <ReviewPanel
+        filename="photo_resize.png"
+        fileSize={512}
+        fileType="PNG"
+        originalSize={1024}
+        downloadUrl="/api/v1/download/job-1/photo_resize.png"
+        onUndo={() => {}}
+        onStartOver={() => {}}
+        currentToolId="resize"
+        {...props}
+      />
+    </MemoryRouter>,
+  );
+}
+
+describe("ReviewPanel library saved state (issue #495)", () => {
+  afterEach(() => {
+    cleanup();
+  });
+
+  it("shows the manual save link when the result was not auto-saved", () => {
+    renderPanel();
+
+    expect(screen.getByRole("button", { name: /save to files/i })).toBeDefined();
+    expect(screen.queryByRole("link", { name: /view in files/i })).toBeNull();
+  });
+
+  it("replaces the manual save link with the saved indicator after an auto-save", () => {
+    renderPanel({ savedLibraryFileId: "lib-copy" });
+
+    expect(screen.getByText("Saved to Files")).toBeDefined();
+    expect(screen.getByRole("link", { name: /view in files/i })).toBeDefined();
+    // The manual save button must be gone: clicking it would create a duplicate
+    expect(screen.queryByRole("button", { name: /save to files/i })).toBeNull();
+  });
+
+  it("shows neither control for data-output tools", () => {
+    renderPanel({ currentToolId: "ocr", savedLibraryFileId: "lib-copy" });
+
+    expect(screen.queryByRole("button", { name: /save to files/i })).toBeNull();
+    expect(screen.queryByRole("link", { name: /view in files/i })).toBeNull();
+  });
+});