docs: publish docs/ to the GitHub wiki and reorganise the user guide

- scripts/publish-wiki.sh publishes every page listed in SECTIONS, copies
  images, writes a sectioned sidebar and footer, and removes stale pages.
  --check fails on links to missing files or headings and on docs pages
  that are neither published nor excluded.
- New wiki.yml runs the check on pull requests and pushes to main, and
  publishes when release.yml calls it or when started by hand.
- Split USER_GUIDE.md into topic pages (files, synced folders, photos,
  sharing, computers, launcher and tray); add Getting started and FAQ.
- Make the COPR repository the main Fedora path, with update and
  uninstall steps for every package type.
- Fix the stale CAPTCHA note in CLI.md, document pdfs unlock and lock,
  and drop the broken AGENTS.md link from CONTRIBUTING.md.

docs/FILES.md

@@ -0,0 +1,88 @@
+# Files and offline access
+
+Your Proton Drive appears on this computer as a folder, `~/ProtonDrive`. Every file and folder in
+it is listed straight away, but a file only downloads when a program opens it. This page covers
+working in that folder, keeping files on this computer, the Trash, and earlier versions of a
+file.
+
+- [Your Drive as a folder](#your-drive-as-a-folder)
+- [Keep files available offline](#keep-files-available-offline)
+- [Browse in the app](#browse-in-the-app)
+- [Trash](#trash)
+- [Earlier versions of a file](#earlier-versions-of-a-file)
+- [Choose which program opens a file](#choose-which-program-opens-a-file)
+
+## Your Drive as a folder
+
+`~/ProtonDrive` is your Proton Drive, called **My files** in the app. It is not a copy. A file you
+change there changes on Proton Drive, and a file you delete there goes to the Proton Drive
+Trash. Every program can use it, from your file manager to a terminal.
+
+- **Only what you read is downloaded.** A video player that seeks, or a tool that reads only the
+  start of a file, downloads only those parts. Videos and music start playing before the whole
+  file is down.
+- **Changes are instant, online or offline.** Creating, renaming, moving and deleting return at
+  once. When a program saves and closes a file, the new content is stored on this computer and
+  sent to Proton Drive in the background. Changes survive a lost connection, a crash or a reboot.
+  See [Changes waiting for Proton Drive](SYNCED_FOLDERS.md#changes-waiting-for-proton-drive).
+- **Recently opened files are cached** up to a size limit (5 GiB by default, set in
+  **Preferences → Storage**). The oldest are removed first to make room.
+- **Shared with me** is a folder inside `~/ProtonDrive` that holds what other people share with
+  you. Shares where you are a viewer are read-only.
+
+Proton Drive cannot store symbolic links, hard links, device files or FIFOs. A program that tries
+to create one gets an error at once. For a project that needs them, use a
+[synced folder](SYNCED_FOLDERS.md) and exclude those paths.
+
+To move the folder somewhere else, change **Preferences → General → Location**.
+
+## Keep files available offline
+
+Files you mark **Available offline** are downloaded completely and stay on this computer, so
+they open without a connection.
+
+- **In the app:** select a file or folder in **My files** and turn on **Available offline**.
+- **From a terminal:** `pdfs pin ~/ProtonDrive/Documents/Taxes`
+
+For a folder, every file in it and in its subfolders downloads in the background. The tray and
+the app show the progress. **Preferences → Storage → Available offline** and `pdfs pins` list
+what is kept.
+
+Turn it off again with the same switch, or `pdfs unpin PATH`. This frees the space. The files stay
+on Proton Drive. A file inside a folder that is kept offline stays with its folder: turn the
+folder off instead.
+
+## Browse in the app
+
+![My files in the app](../images/files.png)
+
+The **My files** page shows the same files without going through the folder. It has a grid and
+a list view, sorting, thumbnails (including camera RAW previews), multi-select, and drag and drop
+to upload. **Details** (Alt+Enter) shows the size, dates, sharing and version history of the
+selected item.
+
+## Trash
+
+Deleted files go to the Trash, both from `~/ProtonDrive` and from the app. The **Trash** page
+lists them with the date they were deleted.
+
+- **Restore** puts an item back where it was, together with any trashed folders above it.
+- **Delete Forever** and **Empty Trash** are permanent.
+
+From a terminal: `pdfs trash` lists the Trash with an ID for each item, and `pdfs restore`,
+`pdfs delete-forever` and `pdfs empty-trash` take those IDs.
+
+## Earlier versions of a file
+
+Proton Drive keeps earlier versions of every file. Open them with **Details → Versions…** in the
+app, or `pdfs versions list PATH`. You can:
+
+- **Restore** a version. This happens on Proton Drive, so nothing is uploaded again.
+- **Save** a version to a separate file, without touching the current one.
+- **Delete** an old version permanently. The current version cannot be deleted.
+
+## Choose which program opens a file
+
+The app and the search launcher open files with your desktop's default program (`xdg-open`). To
+open some file types differently, for example text files in Neovim inside a terminal, add
+`open_with` rules to `config.json`. See [Configuration → `open_with`](CONFIGURATION.md#open_with).