Fix keyboard shortcut scoping; add tab switching with Ctrl+Alt+PgUp/Down

- Use sentinel element to properly clean up detail view Ctrl+E listener
- Single document listener per view handles all shortcuts regardless of focus
- Ctrl+S/D now work from preview tab and title input without separate listeners
- Ctrl+Alt+PageUp/Down switches Write/Preview tabs

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

public/app.mjs

@@ -656,15 +656,18 @@ function render_entry_detail(container) {
 	const et = state.entry_types.find(t => t.id === entry.type);
 	const back_hash = 'type/' + entry.type;
 
+	const sentinel = document.createElement('div');
 	const on_keydown = e => {
 		if (e.ctrlKey && e.key === 'e') { e.preventDefault(); navigate('edit/' + entry.id); }
 	};
 	document.addEventListener('keydown', on_keydown);
 	const observer = new MutationObserver(() => {
-		if (!container.isConnected) { document.removeEventListener('keydown', on_keydown); observer.disconnect(); }
+		if (!sentinel.isConnected) { document.removeEventListener('keydown', on_keydown); observer.disconnect(); }
 	});
 	observer.observe(document.body, { childList: true, subtree: true });
 
+	container.appendChild(sentinel);
+
 	// Header
 	const header = document.createElement('div');
 	header.className = 'detail-header';
@@ -843,6 +846,13 @@ function render_edit_view(container) {
 	tab_bar.appendChild(write_tab);
 	tab_bar.appendChild(preview_tab);
 
+	const tabs = [write_tab, preview_tab];
+	function switch_tab(dir) {
+		const current = tabs.findIndex(t => t.classList.contains('active'));
+		const next = (current + dir + tabs.length) % tabs.length;
+		tabs[next].click();
+	}
+
 	// CodeMirror editor
 	const cm_host = document.createElement('div');
 	cm_host.className = 'edit-cm-host';
@@ -861,8 +871,6 @@ function render_edit_view(container) {
 					...defaultKeymap,
 					...historyKeymap,
 					indentWithTab,
-					{ key: 'Ctrl-s', mac: 'Cmd-s', run: () => { save_btn.click(); return true; } },
-					{ key: 'Ctrl-d', run: () => { cancel_btn.click(); return true; } },
 				]),
 				EditorView.lineWrapping,
 				placeholder('Body (markdown)'),
@@ -909,10 +917,18 @@ function render_edit_view(container) {
 	});
 
 	// Ctrl+S on title input
-	title_input.addEventListener('keydown', e => {
+
-		if ((e.ctrlKey || e.metaKey) && e.key === 's') { e.preventDefault(); save_btn.click(); }
+	const on_edit_keydown = e => {
-		if ((e.ctrlKey || e.metaKey) && e.key === 'd') { e.preventDefault(); cancel_btn.click(); }
+		if ((e.ctrlKey || e.metaKey) && e.key === 's')            { e.preventDefault(); save_btn.click(); }
+		if ((e.ctrlKey || e.metaKey) && e.key === 'd')            { e.preventDefault(); cancel_btn.click(); }
+		if (e.ctrlKey && e.altKey && e.key === 'PageUp')   { e.preventDefault(); switch_tab(-1); }
+		if (e.ctrlKey && e.altKey && e.key === 'PageDown') { e.preventDefault(); switch_tab(+1); }
+	};
+	document.addEventListener('keydown', on_edit_keydown);
+	const edit_observer = new MutationObserver(() => {
+		if (!view.isConnected) { document.removeEventListener('keydown', on_edit_keydown); edit_observer.disconnect(); }
 	});
+	edit_observer.observe(document.body, { childList: true, subtree: true });
 
 	// --- Sidebar ---
 	const sidebar = document.createElement('div');