[Doxygen] More picture docs (#7220)

* [Doxygen] More picture docs

Took 12 minutes

Took 8 minutes

* [Doxygen] Move custom card pictures page into card_pictures subfolder

The actual cyclic dependency fix is converting the mutual @subpage
reference from custom_card_pictures to fixing_card_pictures into a
plain @ref, so the page hierarchy no longer loops back on itself.

* [Doxygen] Correct card-picture docs per review

* fix table layout

* [Doxygen] Deduplicate placeholder table and document image overrides

- Make custom_card_pictures.md the canonical home of the URL reference-point
  table; loading_card_pictures.md cross-references it through @ref instead of
  maintaining a second copy (unaddressed review comment).
- Switch the remaining @subpage custom_card_pictures to @ref in
  fixing_card_pictures.md so the page keeps its single parent under
  user_reference.
- Document the Image Overrides feature added in #7311/#7312 on the user page,
  loading_card_pictures.md and fixing_card_pictures.md: local override storage,
  the downloadedPics root lookup, exact file-name matching, and the set-folder
  vs flat export naming schemes.

* Update doc/doxygen/extra-pages/user_documentation/card_pictures/custom_card_pictures.md

Co-authored-by: tooomm <tooomm@users.noreply.github.com>

---------

Co-authored-by: Lukas Brübach <Bruebach.Lukas@bdosecurity.de>
Co-authored-by: tooomm <tooomm@users.noreply.github.com>

doc/doxygen/extra-pages/user_documentation/troubleshooting/fixing_card_pictures.md

@@ -28,7 +28,8 @@ valid URLs. If you suspect the list has been modified or corrupted, press 'Reset
 defaults.
 
 For information on how to add your own custom URL templates, see the 'How to add a custom URL' link in the same
-settings section.
+settings section, or @ref custom_card_pictures for a full reference of the URL reference points, the CUSTOM
+pictures folder, and custom card databases.
 
 # Check Your Local Picture Folder
 
@@ -41,8 +42,12 @@ Cockatrice checks the following locations, in order:
 - The custom pictures folder (recursively indexed by file name).
 - `<pictures directory>/<set code>/<card file name>`
 - `<pictures directory>/downloadedPics/<set code>/<card file name>`
+- `<pictures directory>/downloadedPics/<card file name>` (for export naming schemes without a set folder)
 
-The following import naming schemes are recognized (using both `_` and `-` as separators):
+A file only matches when its name without the extension equals one of the recognized scheme patterns exactly.
+
+The following import naming schemes are recognized (using both `_` and `-` as separators). The canonical table with
+concrete example file names is on @ref custom_card_pictures:
 
 | Scheme                      | Pattern                    |
 | --------------------------- | -------------------------- |
@@ -56,6 +61,10 @@ If a picture you downloaded or placed manually is wrong, stale, or corrupted, de
 attention to the `downloadedPics` subfolder: this is where the filesystem caching method writes downloaded images, and
 after a provider outage it can permanently contain the wrong printing until you delete it manually.
 
+If a card persistently shows artwork you assigned yourself, you may have an **image override** set for it. Right-click
+the card in the deck editor's printing selector and use 'Image Overrides' → 'Clear Custom Image' to remove it (or
+delete the stored `.png` in `downloadedPics/`). See @ref custom_card_pictures for details.
+
 See @ref loading_card_pictures for details on how local images are loaded.
 
 # Clear Caches