Move the browser suites into the repository

They lived in a scratch directory under /tmp, which was cleared overnight;
four of the five were simply gone. Whatever they were worth, they were
worth nothing kept there.

Rewritten against a shared lib.mjs. The old ones registered their users
through the sign-up form, which no longer exists — each suite now creates
a throwaway account through the admin API and deletes it afterwards, so a
run leaves the database as it found it. The previous generation left nine
accounts behind; those are gone too.

Three test hooks went into the app, each of which earns its place beyond
testing: aria-label on the note title (the sidebar search box is also a
text input, and a screen reader could not tell them apart either),
data-note-row on list rows, data-user on admin rows.

Two suites were flaky in ways worth naming, because both were the test
misreading the app rather than the app misbehaving:
- ticking a task then inserting a note link put the link inside the task
  list, since Control+End lands there. Verified against the server that
  the tick itself persists correctly; the suite now leaves the list first
  and asserts where the link ended up.
- the note-title lookup matched the sidebar's Trash entry, which wears the
  same emoji as a note row.

56 checks across five suites, all passing.

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

e2e/editor.mjs

@@ -0,0 +1,110 @@
+/* Editor: tables, task lists, links between notes, and whether any of it
+ * survives a reload — the place where a stale server response used to eat
+ * freshly typed content. */
+import {
+  OUT,
+  check,
+  createNote,
+  createNotebook,
+  insertTable,
+  launch,
+  reopenNote,
+  report,
+  setTitle,
+  typeInEditor,
+  withFreshUser,
+} from "./lib.mjs";
+
+const browser = await launch();
+let session;
+try {
+  session = await withFreshUser(browser, "editor");
+  const p = session.page;
+
+  await createNotebook(p, "Editor Book");
+  await createNote(p);
+  await typeInEditor(p, "Grundtext");
+
+  /* ── tables ── */
+  await insertTable(p);
+  check((await p.locator(".ProseMirror table").count()) > 0, "table inserted");
+  check((await p.locator(".ProseMirror table th").count()) >= 3, "table has a header row");
+
+  /* ── task list ── */
+  await p.locator(".ProseMirror").click();
+  await p.keyboard.press("Control+End");
+  await p.keyboard.press("Enter");
+  await p.getByTitle("Task list").click();
+  await p.waitForTimeout(400);
+  await p.keyboard.type("Milch kaufen");
+  await p.waitForTimeout(1200);
+  check((await p.locator('.ProseMirror input[type="checkbox"]').count()) > 0, "task list inserted");
+  await p.locator('.ProseMirror input[type="checkbox"]').first().click();
+  await p.waitForTimeout(1500);
+
+  await p.screenshot({ path: `${OUT}/editor-content.png` });
+
+  /* ── a second note to link to ── */
+  await setTitle(p, "Quelle");
+  await createNote(p);
+  await setTitle(p, "Ziel");
+  await typeInEditor(p, "Ich bin das Ziel.");
+
+  await p.locator("button").filter({ hasText: "Quelle" }).first().click();
+  await p.waitForSelector(".ProseMirror", { timeout: 15000 });
+  await p.waitForTimeout(1200);
+
+  /* ── note link via the @ menu ── */
+  // Control+End lands inside the task list, where a plain Enter would only make
+  // another task. A second Enter on the empty item leaves the list, so the link
+  // goes into a paragraph of its own and the checked task above stays untouched.
+  await p.locator(".ProseMirror").click();
+  await p.keyboard.press("Control+End");
+  await p.keyboard.press("Enter");
+  await p.keyboard.press("Enter");
+  await p.waitForTimeout(300);
+  await p.keyboard.type("@Ziel");
+  await p.waitForTimeout(1400);
+  const menuOpen = (await p.locator("text=Ziel").count()) > 0;
+  check(menuOpen, "@ opens the link menu");
+  await p.keyboard.press("Enter");
+  await p.waitForTimeout(1800);
+
+  const linkCount = await p.locator('.ProseMirror [data-note-link], .ProseMirror .note-link').count();
+  check(linkCount > 0, "note link inserted into the document", `${linkCount} found`);
+  await p.screenshot({ path: `${OUT}/editor-link.png` });
+
+  /* ── the server learned about it ── */
+  await p.waitForTimeout(1500);
+  await p.locator("button").filter({ hasText: "Ziel" }).first().click();
+  await p.waitForSelector(".ProseMirror", { timeout: 15000 });
+  await p.waitForTimeout(2000);
+  const backlink = await p.locator("text=Quelle").count();
+  check(backlink > 0, "the target shows a backlink to the source");
+
+  /* ── everything survives a cold reload ── */
+  await reopenNote(p, "Quelle");
+  check((await p.locator(".ProseMirror table").count()) > 0, "table survived a reload");
+  check(
+    (await p.locator('.ProseMirror [data-note-link], .ProseMirror .note-link').count()) > 0,
+    "note link survived a reload"
+  );
+  check((await p.locator('.ProseMirror input[type="checkbox"]').count()) > 0, "task list survived a reload");
+  check(
+    (await p.locator('.ProseMirror input[type="checkbox"]:checked').count()) === 1,
+    "the ticked task stayed ticked, and only that one"
+  );
+  check(
+    (await p.locator(".ProseMirror li").filter({ hasText: "Ziel" }).count()) === 0,
+    "the note link went into a paragraph, not into the task list"
+  );
+  check((await p.locator(".ProseMirror").innerText()).includes("Grundtext"), "plain text survived a reload");
+  await p.screenshot({ path: `${OUT}/editor-after-reload.png` });
+} catch (e) {
+  check(false, "suite ran to the end", e.message);
+} finally {
+  await session?.cleanup();
+  const code = report();
+  await browser.close();
+  process.exit(code);
+}