Implement CE-WP-0005 T01-T08: demo app — sessions, uploads, ZIP archive

Turn the MVP into a self-contained demo. Users now:
  1. Land on an empty-state and create a named session.
  2. Drag-drop or pick arbitrary PDFs into that session.
  3. Annotate, build evidence, link to form fields — all session-scoped.
  4. Export the whole session as a single .zip archive (manifest +
     per-document PDFs).
  5. Import a .zip back — into a new session, or merged into an
     existing one (documents deduped by SHA-256 fingerprint;
     annotations/evidence/links added additively).

Architecture:
- New shared types: SessionId, Session, SessionArchiveManifest +
  parseSessionArchiveManifest with schema-version validation.
- SessionService (engine/services/sessions.ts) handles lifecycle
  (create/rename/delete/setActive) + emits 4 new events through its
  own bus; SharedContracts.md §4 lists the additions.
- SessionProvider (work/SessionContext.tsx) owns the cross-session
  state: service, per-session PdfByteStore registry, per-session
  version counter that drives EngineProvider remounts after imports.
- EngineProvider becomes session-aware (sessionId prop drives per-
  session localStorage keys). Bumping engineRevision after
  restoreFromStorage forces consumers to re-render so restored repos
  show up immediately.
- PdfByteStore (source/pdf/byte-store.ts) holds Uint8Array bytes per
  document and mints blob URLs; ingestPdfFromFile is the upload
  entry-point that wraps the existing ingestPdf pipeline.
- ADR-0008 locks the ZIP layout (manifest.json + documents/<id>.pdf),
  the manifest schema (schemaVersion 1), and the merge-on-collision
  policy. JSZip is the only new dependency.
- App.tsx restructured: SessionProvider at the root, EngineProvider
  keyed by ${sessionId}:${version}, hash routing #/s/<id>[/forms/demo],
  SessionMenu top-bar, CreateFirstSession empty state.
- New DocumentRemoved event for per-document delete cleanup in
  CollectionList; engine.documents.remove() is the new service method.

Tests:
- Unit: 16 SessionService lifecycle + persistence tests;
  per-session snapshot round-trip; PdfByteStore + ingestPdfFromFile;
  SessionArchive parser; exportSessionZip + importSessionZip with
  create + merge + corrupt-archive paths.
- DOM: UploadDropzone, session-scoped CollectionList delete,
  SessionMenu create/switch/rename, routing parser.
- E2E: tests/integration/session-export-reimport.dom.test.tsx walks
  the full create → annotate → export → reimport flow and asserts
  the additive merge (deduped doc + doubled evidence rows).
- Legacy E2Es updated to use a seed-session helper instead of the
  removed fixture-button flow.

Known limitation (documented in ADR-0008): re-importing your own
freshly-exported ZIP creates duplicate annotations. Forward pointer
left for an importBundleId follow-up.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

tests/integration/forms-overlay-e2e.dom.test.tsx

@@ -27,8 +27,6 @@ import { act, cleanup, render, screen, waitFor } from "@testing-library/react";
 import userEvent from "@testing-library/user-event";
 import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 
-import type { Document, DocumentRepresentation } from "@shared/document";
-import type { DocumentId, RepresentationId } from "@shared/ids";
 import type { Selector } from "@shared/selector";
 
 import type { PdfSelectionCapture } from "@anchor/index";
@@ -82,37 +80,8 @@ vi.mock("@anchor/index", async (importOriginal) => {
 const FIXTURE = manifest.fixtures.find((f) => f.id === "fristsetzung-bezifferung")!;
 const SYNTHETIC_CANONICAL = ["Pre.", FIXTURE.known_good_quote, "Post."].join(" ");
 
-vi.mock("@source/index", async (importOriginal) => {
-  const original = await importOriginal<typeof import("@source/index")>();
-  return {
-    ...original,
-    ingestPdf: vi.fn(async (_input: unknown, options?: { filename?: string }) => {
-      const documentId = ("doc_test_" + Math.random().toString(36).slice(2, 10)) as DocumentId;
-      const representationId = ("rep_test_" + Math.random().toString(36).slice(2, 10)) as RepresentationId;
-      const document: Document = {
-        id: documentId,
-        mediaType: "application/pdf",
-        ...(options?.filename ? { title: options.filename } : {}),
-        fingerprint: "synthetic-fingerprint-for-test",
-        createdAt: "2026-05-25T00:00:00.000Z",
-        updatedAt: "2026-05-25T00:00:00.000Z",
-      };
-      const representation: DocumentRepresentation = {
-        id: representationId,
-        documentId,
-        representationType: "pdf-text",
-        contentHash: "synthetic-fingerprint-for-test",
-        canonicalText: SYNTHETIC_CANONICAL,
-        pageMap: [{ page: 1, width: 595, height: 842 }],
-        offsetMap: [
-          { page: 1, globalStart: 0, globalEnd: SYNTHETIC_CANONICAL.length, pageLength: SYNTHETIC_CANONICAL.length },
-        ],
-        generatedAt: "2026-05-25T00:00:00.000Z",
-      };
-      return { document, representation };
-    }),
-  };
-});
+// CE-WP-0005: pre-seed a session with the fixture doc; no ingestPdf mock needed.
+import { seedSessionWithDoc } from "./helpers/seed-session";
 
 function syntheticCaptureFor(text: string, page: number): PdfSelectionCapture {
   return {
@@ -135,15 +104,14 @@ describe("CE-WP-0003-T08 — PRD scenario steps 5-9 end-to-end", () => {
     viewerSnapshot.scrollToAnnotationId = null;
     viewerSnapshot.onSelectionCaptured = null;
     globalThis.localStorage?.clear();
-    globalThis.fetch = vi.fn(async () =>
-      new Response(new Uint8Array([0x25, 0x50, 0x44, 0x46]).buffer, {
-        status: 200,
-        headers: { "Content-Type": "application/pdf" },
-      }),
-    );
     if (typeof window !== "undefined") {
       history.replaceState(null, "", window.location.pathname);
     }
+    seedSessionWithDoc({
+      sessionName: "T08-forms",
+      documentTitle: FIXTURE.filename,
+      canonicalText: SYNTHETIC_CANONICAL,
+    });
   });
 
   afterEach(() => {
@@ -159,8 +127,7 @@ describe("CE-WP-0003-T08 — PRD scenario steps 5-9 end-to-end", () => {
       await loadApp();
 
       // Steps 1-4 (CE-WP-0002 setup): create an evidence item in Review mode.
-      const fixtureBtn = screen.getByRole("button", { name: new RegExp(FIXTURE.id) });
-      await user.click(fixtureBtn);
+      // CE-WP-0005: doc pre-seeded into the session — skip fixture click.
       await waitFor(() => expect(viewerSnapshot.onSelectionCaptured).not.toBeNull());
       await act(async () => {
         viewerSnapshot.onSelectionCaptured!(
@@ -175,9 +142,10 @@ describe("CE-WP-0003-T08 — PRD scenario steps 5-9 end-to-end", () => {
       await user.click(screen.getByRole("button", { name: /Save evidence/ }));
       await screen.findByText(/Overlay E2E evidence/);
 
-      // Step 5: navigate to /forms/demo via the top-bar.
+      // Step 5: navigate to forms via the top-bar.
       await user.click(screen.getByRole("button", { name: "Forms" }));
-      expect(window.location.hash).toBe("#/forms/demo");
+      // CE-WP-0005: route is now session-scoped.
+      expect(window.location.hash).toMatch(/^#\/s\/sess_[^/]+\/forms\/demo$/);
 
       // Step 6: stage the evidence in the strip, then click the summary
       // field to create the link.