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

app/test/app_widget_test.dart

@@ -1185,6 +1185,63 @@ void main() {
     await tester.pumpAndSettle();
     expect(find.textContaining('1 unread post'), findsOneWidget);
   });
+
+  testWidgets('marked text can be kept as a quotation', (tester) async {
+    final source = '''
+<?xml version="1.0" encoding="UTF-8"?>
+<html xmlns="http://www.w3.org/1999/xhtml">
+  <head><title>Cats</title>
+    <meta name="mews-profile" content="0.1" />
+    <meta name="author" content="A. Author" />
+  </head>
+  <body><p>The finest sentence about cats ever written.</p></body>
+</html>
+''';
+    final stubDeps = AppDependencies(
+      database: MewsDatabase.test(NativeDatabase.memory()),
+      fetch: FakeFetch({'https://example.com/cats.html': source}),
+      strings: strings,
+    );
+    await tester.pumpWidget(MewsApp(deps: stubDeps, strings: strings));
+    await tester.pumpAndSettle();
+
+    await stubDeps.browser.open('https://example.com/cats.html');
+    await tester.pumpAndSettle();
+
+    // A long press on the word 'written' selects it and shows the toolbar.
+    // The press lands on the glyphs: a wrapped line's geometric center can
+    // sit between the lines, where no word is. The word is on the page's
+    // second line, where the toolbar fits above it; on the first line the
+    // toolbar would open past the top of the screen.
+    final paragraph = tester.renderObject<RenderParagraph>(
+        find.descendant(
+            of: find.textContaining('finest sentence'),
+            matching: find.byType(RichText)));
+    final plain = paragraph.text.toPlainText();
+    final word = plain.indexOf('written');
+    final box = paragraph
+        .getBoxesForSelection(
+            TextSelection(baseOffset: word, extentOffset: word + 7))
+        .first;
+    final onWord = paragraph.localToGlobal(
+        Offset((box.left + box.right) / 2, (box.top + box.bottom) / 2));
+    final gesture = await tester.startGesture(onWord);
+    await tester.pump(const Duration(milliseconds: 600));
+    await gesture.up();
+    await tester.pumpAndSettle();
+
+    await tester.tap(find.text('Save as quotation'));
+    await tester.pumpAndSettle();
+
+    // The selection kept its page: address, title and the author the page's
+    // metadata named.
+    final kept = await stubDeps.db.quotationsList();
+    expect(kept, hasLength(1));
+    expect(kept.single.pageUrl, 'https://example.com/cats.html');
+    expect(kept.single.pageTitle, 'Cats');
+    expect(kept.single.author, 'A. Author');
+    expect(kept.single.quote, contains('written'));
+  });
 }
 
 MewsPage parseSource(String source, String url) =>