feat: pick page icons and widen pages per device

[AmrMsCLL]

Notes step N5.

• Page icon: a button beside the title opens a picker of 24 emoji (or Remove the icon). It uses the existing notes.icon field, so icons show in the page tree, the Pages list and Home.
• Full width: pages (not boards or databases) get a Full width / Standard width toggle. The plan suggested storing this on the page, which needs a new column; to avoid a migration it is kept per device for now (localStorage, falling back to memory when storage is blocked).
• The sidebar page tree now refreshes when a page is renamed or its icon changes, through a small announcePagesChanged / onPagesChanged signal in notes.ts.
• The page tree's storage write now only ignores storage errors (DOMException).

Checked in the browser (local stack): picking 🍳 saved the icon and showed it beside the title. Tests: new icon and width case in test/notes.spec.tsx, lint, type check.