fix: init robuste avant <body>, pas de repli tardif au-dessus de l'écran, README

- écoute freshrss:load-more sur document (script async possiblement exécuté
  avant le parsing de <body>)
- ne replie jamais après coup un article qui commence au-dessus de l'écran :
  la page sauterait et des articles non vus seraient marqués lus
- README : l'image officielle n'a pas git, installation depuis l'hôte

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/unit/read-more.test.js

@@ -143,3 +143,40 @@ test('init handles load-more', () => {
 	assert.equal(document.querySelectorAll('.read-more-btn').length, 2);
 	assert.equal(document.getElementById('flux_2').dataset.readMore, 'collapsed');
 });
+
+test('init works before body is parsed', () => {
+	const { window, document, ReadMore } = setup([]);
+	document.documentElement.removeChild(document.body);
+	setContext(window, 'reader');
+	assert.doesNotThrow(() => ReadMore.init(window, measure));
+	const body = document.createElement('body');
+	body.innerHTML = entry(1, 1000);
+	document.documentElement.appendChild(body);
+	body.dispatchEvent(new window.Event('freshrss:load-more', { bubbles: true }));
+	assert.equal(document.getElementById('flux_1').dataset.readMore, 'collapsed');
+});
+
+test('late image load does not collapse entry already above viewport top', () => {
+	const { window, document, ReadMore } = setup([entry(1, 300)]);
+	setContext(window, 'reader');
+	ReadMore.init(window, measure);
+	const flux = document.getElementById('flux_1');
+	flux.getBoundingClientRect = () => ({ top: -100, bottom: 200 });
+	const text = flux.querySelector('.text');
+	text.dataset.h = '1000';
+	text.querySelector('img').dispatchEvent(new window.Event('load'));
+	assert.ok(!text.classList.contains('read-more-collapsed'));
+	assert.equal(flux.querySelectorAll('.read-more-btn').length, 0);
+});
+
+test('load-more does not collapse short entry already above viewport top', () => {
+	const { window, document, ReadMore } = setup([entry(1, 300)]);
+	setContext(window, 'reader');
+	ReadMore.init(window, measure);
+	const flux = document.getElementById('flux_1');
+	flux.getBoundingClientRect = () => ({ top: -100, bottom: 200 });
+	flux.querySelector('.text').dataset.h = '1000';
+	document.body.dispatchEvent(new window.Event('freshrss:load-more', { bubbles: true }));
+	assert.equal(flux.dataset.readMore, 'short');
+	assert.equal(flux.querySelectorAll('.read-more-btn').length, 0);
+});