feat: add quotations from marked text, with citations and sharing

app/test/database_test.dart

@@ -231,4 +231,61 @@ void main() {
     expect(await db.allClientCertificates(), isEmpty);
     expect(await db.bindingFor('capsule.example', 1965), isNull);
   });
+  test('quotations are saved with their page and narrow by a search', () async {
+    await db.addQuotation(
+      quote: 'A fine sentence about cats.',
+      pageUrl: 'https://example.com/cats.html',
+      pageTitle: 'On cats',
+      author: 'A. Author',
+    );
+    await db.addQuotation(
+      quote: 'A dog is a dog is a dog.',
+      pageUrl: 'https://example.com/dogs.html',
+    );
+    expect(await db.countQuotations(), 2);
+
+    // Saved within the same clock tick, the id tiebreak keeps the order they
+    // were saved in; the page's title and author ride along.
+    final kept = await db.quotationsList();
+    expect(kept.first.pageUrl, 'https://example.com/cats.html');
+    expect(kept.first.pageTitle, 'On cats');
+    expect(kept.first.author, 'A. Author');
+
+    // A search matches the quoted text, the title, the author or the
+    // address; it does not have to know which one it hit.
+    expect((await db.quotationsList(query: 'cats')).length, 1);
+    expect((await db.quotationsList(query: 'Author')).single.pageUrl,
+        'https://example.com/cats.html');
+    expect((await db.quotationsList(query: 'dogs.html')).single.quote,
+        'A dog is a dog is a dog.');
+
+    // Ordered by page, a page without a title sorts under its address.
+    final byPage = await db.quotationsList(sort: QuotationSort.page);
+    expect(byPage.first.pageUrl, 'https://example.com/cats.html');
+
+    // A quotation of a page the reader's site lists as a post carries the
+    // site's own title, so its citation can name it.
+    await db.addSubscription('https://example.com/index.html', 'Signal Bars', null);
+    await db.addEntries('https://example.com/index.html',
+        [_entry('https://example.com/2026-10-08-retro.html')]);
+    await db.addQuotation(
+      quote: 'The finest retro handsets.',
+      pageUrl: 'https://example.com/2026-10-08-retro.html',
+      pageTitle: 'Collecting retro phones',
+    );
+    final post = (await db.quotationsList())
+        .firstWhere((q) => q.pageUrl.contains('retro'));
+    expect(post.siteTitle, 'Signal Bars');
+    expect(await db.siteTitleOf('https://example.com/index.html'),
+        'Signal Bars');
+    expect(await db.siteTitleOf('https://unknown.example/'), isNull);
+
+    // One quotation by its id, for the actions that share or remove it.
+    final id = kept.last.id;
+    expect((await db.quotationById(id))?.quote, 'A dog is a dog is a dog.');
+    await db.removeQuotation(id);
+    expect(await db.quotationById(id), isNull);
+    // The retro quotation from the site-title check remains.
+    expect(await db.countQuotations(), 2);
+  });
 }