fix(web): lecteurs EPUB/PDF — gestion d'erreurs, worker pdf.js local

Composant ReaderError avec diagnostic et actions de repli, worker
pdf.js servi localement (pdfWorker) pour éviter les CDN, typage du
view foliate, navigation retour vers la fiche livre et styles lecteur
associés.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

apps/web/src/reader/readerRuntime.test.ts

@@ -0,0 +1,20 @@
+import { describe, expect, it } from "vitest";
+import { epubFileName } from "./EpubReader";
+import { pdfWorkerSrc } from "./pdfWorker";
+import { readerErrorMessage } from "./ReaderError";
+
+describe("reader runtime helpers", () => {
+  it("extracts an EPUB file name from the file URL", () => {
+    expect(epubFileName("http://readabook.local/books/12/file?token=abc")).toBe("book.epub");
+    expect(epubFileName("http://readabook.local/files/example.epub")).toBe("example.epub");
+  });
+
+  it("keeps PDF.js worker source on the bundled module worker", () => {
+    expect(pdfWorkerSrc).toContain("pdf.worker.min.mjs");
+  });
+
+  it("normalizes reader technical errors", () => {
+    expect(readerErrorMessage(new Error("Setting up fake worker failed"), "PDF indisponible")).toBe("Setting up fake worker failed");
+    expect(readerErrorMessage("", "EPUB indisponible")).toBe("EPUB indisponible");
+  });
+});