Uber Notebook 1.1.3

Release notes in the app, a shorter README, and fixes from the first issue and pull requests.

Added

• Settings → What's new: every release's notes, newest first, the latest open. It reads the notes that come with the app, so it works offline.
• After an update, the sidebar says once which version you're on, with What's new.

Changed

• A shorter README. Everything in detail is in docs/guide.md, the security details in SECURITY.md, how it works in docs/how-it-works.md, and this changelog is reorganized.

Fixed

• The window opens without qt6-webengine installed; only a PDF's pages don't show then (#1, reported by @UnderStackDev).
• Agents get long answers in full: blocks or read on a big page used to be cut off. A long answer now comes as a file to read.
• Changing a big open page's title, icon or cover no longer answers "omarchy-shell is not responding", and you stay where you were on the page.
• Markdown export keeps text that looks like a heading or a list item as text, a code block with a fence line inside as one block, and a heading with a line break as one heading (#3, thanks @nixfred).
• Calendar import keeps an event's notes when it has an alert, and backslashes in notes (contacts' too); a middle name goes after the given name; a 29 February with no year is the next one (#4, thanks @nixfred).
• #constructor and similar names can't break tags or notebook ids (#5, thanks @nixfred).
• Importing a folder that's hidden, or inside a hidden one, finds its files; a window rule Hyprland refused is tried again (#6, thanks @nixfred).
• Imports keep notes between two --- lines at the top, link and footnote lines in code samples, an email body line that starts like a boundary, and a heading or list after an unclosed paragraph (#7, thanks @nixfred).
• The tests run on a fresh clone (#2, thanks @nixfred).

Security

• The files helper refuses a file that says it's empty but isn't (like /proc/self/environ), whatever the size limit (#2, thanks @nixfred).