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/SYNCED_FOLDERS.md

@@ -0,0 +1,163 @@
+# Synced folders
+
+A synced folder is an ordinary folder on this computer, for example `~/Documents`, that is backed
+up to Proton Drive and kept in step with it. This page covers adding one, what to do with files
+that should not be backed up, changes that are still waiting to upload, conflicts, and pausing.
+
+- [Add a folder](#add-a-folder)
+- [Synced or online only](#synced-or-online-only)
+- [Move files between synced folders and My files](#move-files-between-synced-folders-and-my-files)
+- [Stop syncing a folder](#stop-syncing-a-folder)
+- [Excluding files with `.pdfsignore`](#excluding-files-with-pdfsignore)
+- [Changes waiting for Proton Drive](#changes-waiting-for-proton-drive)
+- [Conflicts](#conflicts)
+- [Pausing and limiting sync](#pausing-and-limiting-sync)
+
+![Synced folders in the app](../images/sync.png)
+
+## Add a folder
+
+- **In the app:** open **Computers** and choose **Add Folder to Sync**.
+- **From a terminal:** `pdfs sync add ~/Documents`
+
+The folder is backed up under this computer's name. It shows on the **Computers** page of the app
+and in the Proton Drive web app.
+
+From then on, changes go both ways:
+
+- A file you change here uploads a few seconds after the program closes it. A file that a
+  program still holds open for writing waits until it is closed.
+- A file changed somewhere else downloads on the next sync pass.
+
+**Sync → Folders** in the app, and `pdfs sync list`, show every synced folder and its state.
+
+To sync the same folders on two computers, see [Syncing several computers](COMPUTERS.md#syncing-several-computers).
+
+## Synced or online only
+
+A synced folder normally keeps a full copy on this computer. You can switch it to **Online
+only**: the files stay visible in the same place, but take no disk space until you open them, the
+same as in `~/ProtonDrive`.
+
+- **In the app:** use the **Synced / Online only** switch on the folder's card.
+- **From a terminal:** `pdfs sync mode ID ondemand`, and `pdfs sync mode ID mirror` to switch
+  back. `pdfs sync list` shows the ID.
+
+The switch waits until everything in the folder is on Proton Drive. It refuses while the folder
+holds something that never goes there, such as an excluded `.git/` folder, a symbolic link, or a
+folder you may not read. The message names what is in the way.
+
+`pdfs locations` lists every place on this computer the Proton Drive service uses.
+
+## Move files between synced folders and My files
+
+`~/ProtonDrive`, each online-only folder and each synced folder are separate places for your
+system. Moving a file between them with `mv` or a file manager copies and then deletes: every file
+is downloaded, uploaded again, and the original goes to the Trash.
+
+Use **Move to…** in the app or `pdfs move` instead. The move happens on Proton Drive and takes
+seconds, whatever the size:
+
+```sh
+pdfs move ~/Documents/Scans ~/ProtonDrive/Archive
+pdfs move ~/Documents/a.pdf ~/Documents/b.pdf ~/ProtonDrive/Archive
+```
+
+The last path is the destination folder. Everything before it moves there.
+
+A move out of a synced folder waits until its files are on Proton Drive. A file that is still
+uploading, has changes that are not uploaded yet, or is excluded by `.pdfsignore` stops the move,
+and the message names it. Files you already opened in an online-only folder are not downloaded
+again when they move into a synced one.
+
+## Stop syncing a folder
+
+**Stop Syncing** in the app, or `pdfs sync rm ID`, keeps both the local files and the copy on
+Proton Drive. To delete the copy on Proton Drive as well, tick **Also delete from Proton Drive**,
+or add `--delete-remote`.
+
+## Excluding files with `.pdfsignore`
+
+Synced folders skip build output, dependency folders and editor leftovers. Two sets of rules
+apply together:
+
+1. A `.pdfsignore` file at the top of the synced folder (`.protonignore` works too). It uses the
+   same syntax as `.gitignore`, including `!` to include something again:
+
+   ```gitignore
+   build/
+   *.log
+   !important.log
+   ```
+
+2. The `ignore_patterns` list in `config.json`, for every synced folder (see
+   [Configuration](CONFIGURATION.md#ignore_patterns)). When you have not set it, it skips
+   `.git/`, `.hg/`, `.svn/`, `node_modules/`, `target/`, `.venv/`, `__pycache__/`, `*~`,
+   `*.swp`, `*.tmp`, `.DS_Store` and `Thumbs.db`.
+
+Rules are read again on every sync pass. Excluding never deletes anything: a file that becomes
+excluded is no longer synced, and its copy on Proton Drive stays.
+
+A folder you may not read, such as a cache that a container created as root, is skipped the same
+way, and the activity feed mentions it once. Add it to `.pdfsignore` to stop the message.
+
+## Changes waiting for Proton Drive
+
+A change you make exists only on this computer until it reaches Proton Drive. `pdfs status`, the
+tray and **Sync → Overview** count what is still waiting, and `pdfs sync queue` lists it.
+
+Sometimes Proton Drive refuses a change: the storage is full, a share was taken away, the folder
+is gone, the folder holds too many items, or Proton Drive does not accept the name. The change
+then needs you. It shows at once in **Sync → Overview**, in the tray and in `pdfs sync issues`,
+with what it means and what you can do. The file or folder also gets a warning badge in
+**Files**. Hover over it to see why.
+
+Nothing is deleted. The change stays queued and is tried again. You can:
+
+- **Retry** it now, for example after freeing space: the same list, or `pdfs sync retry`.
+- **Export** a file's content to keep your version: `pdfs sync export ID FILE`.
+- **Discard** the change: `pdfs sync discard ID`. It is undone here and never sent. A new file or
+  folder goes away, and anything else goes back to what Proton Drive has. Export first if you want
+  to keep the content.
+
+Two cases are not refused, and the activity log records both:
+
+- A new file or folder whose name is already taken on Proton Drive, by something this computer
+  had not seen yet, lands under a `(sync-conflict …)` name. See [Conflicts](#conflicts).
+- A new file whose folder was deleted on another device in the meantime lands at the top of My
+  files, so its content is not lost.
+
+> [!IMPORTANT]
+> Before you switch off or wipe a computer for good, check that nothing is waiting. Changes that
+> have not reached Proton Drive are lost with the machine. See
+> [Recovery](RECOVERY.md#lost-with-the-machine).
+
+## Conflicts
+
+![Sync history with resolved conflicts](../images/conflicts.png)
+
+When the same file changed on this computer and somewhere else since the last sync, neither
+version is thrown away:
+
+- The other version keeps the original name.
+- Your local version is kept as a copy named like
+  `report (sync-conflict laptop 1759068180).odt`. `laptop` is the computer that made the copy,
+  and the number is the time of the conflict. Copies made before 3.5.0 have no computer name.
+
+Conflicts show under **Sync → Overview → Needs attention** and in `pdfs conflicts`. For each one,
+keep the original, keep the copy, or keep both under a new name:
+
+```bash
+pdfs conflicts
+pdfs conflicts resolve "Documents/report (sync-conflict laptop 1759068180).odt" --keep copy
+```
+
+The version you do not keep goes to the Trash, so a wrong choice can be undone.
+
+## Pausing and limiting sync
+
+- **Pause** from the tray, the **Sync** page, or `pdfs sync pause`. Uploads and synced folders
+  wait, and opening files keeps working. `pdfs sync pause --for 1h` resumes by itself, and
+  `pdfs sync resume` continues at once.
+- **Limit bandwidth** under **Preferences → General → Network**, or with
+  `pdfs sync limit --up 2M --down 10M`. `0` removes a limit.