Issue! - Fix organizing documents

References: #3591, #8805 --- Description Outline currently forces us to create “fake folders” by making empty pages just to organize documents. This clutters the sidebar, breaks mental models on mobile, and makes deep hierarchies impossible. Circling back to the conversation in #8805 (which was ignored) and the long-standing request in #3591 (also ignored), this feature request proposes simply letting us organize our damn documents - real, infinitely-nestable folder abstraction that can contain: • Documents • Attachments (images, PDFs, etc.) • Other Folders All without resorting to blank pages as stand-ins. Literally how normal file systems have worked for decades. This is essential. --- Proposed Solution 1. Database - Add a new folders table (UUID PK, name, optional parentId → folders.id, teamId, timestamps, paranoid deletes). - Add nullable folderId FKs on documents and attachments (on delete: SET NULL). 2. Mo…