Capture into Letter.md from anywhere

Create letters from mobile share sheets, system shortcuts, widgets, and document links.

Mobile capture now reduces the distance between noticing something and saving it as Markdown.

What changed

Send text, links, and photos to Letter.md from the iOS Share Extension.
Use Android's system share action to create a new letter from other apps.
Start a new letter or search from iOS Shortcuts, App Intents, the home-screen widget, and Android launcher shortcuts.
Open supported Letter.md links in the matching native document.
Queue captured content safely when the app or network is not ready.

Shared photos enter the normal Asset upload flow instead of being embedded as fragile temporary URLs.