Moments: per-user saved pages and regions with one category (BL-0055)

Reader: bookmark button and M save the page (Flow: page at the reading
line, Book: the spread) with an optional dragged region, exactly one
category (Twist, Hot, Awesome, Cute, Funny, Feels) and a note. I now
toggles the bars; ? lists all keys. Keys dispatch through public/keys.js,
which also feeds the new Settings -> Keyboard shortcuts section.

Manga page: "Your moments" strip of crops (story or recent order,
category filters), viewer with step, full page, edit, delete and
"Open in reader" (read.html ...&p=). Moments point at pages by file
name and show "page moved" when the file is gone. Private per user.

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

public/settings.js

@@ -140,6 +140,7 @@
   const oldPw = h('input', { type: 'password', autocomplete: 'current-password', placeholder: 'Current password' });
   const newPw = h('input', { type: 'password', autocomplete: 'new-password', placeholder: 'New password' });
   const pwMsg = h('span', { class: 'small' });
+  section('user/shortcuts').append(h('section', { class: 'card' }, keyTable()));
   section('user/account').append(h('section', { class: 'card' },
     h('h2', {}, 'Account · ' + me.name),
     h('div', { class: 'row' }, oldPw, newPw, h('button', { class: 'btn', onclick: async () => {