[Doxygen] Address review feedback on troubleshooting docs

- enabling_debug_logs.md: use shell code fence for terminal commands,
  add export alternative for macOS
- fixing_card_pictures.md: split log section into 'Check Logs' and
  'Enable Picture Loader Debug Logs', remove hardcoded URL list
  (defaults may drift), remove redundant Scryfall/Gatherer note
  (covered in Provider Accuracy section)

Took 1 minute

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

@@ -56,11 +56,13 @@ altogether. Note that this copy may be replaced when you update the client.
 Open the Terminal app (it is in 'Applications → Utilities') and run the following two commands, replacing the path
 with the full location of your file:
 
-```text
+```shell
 launchctl setenv QT_LOGGING_CONF /path/to/qtlogging.ini
 open -a Cockatrice
 ```
 
+You can also use `export QT_LOGGING_CONF=/path/to/qtlogging.ini` to set the variable for the current terminal session.
+
 The setting stays active until you log out or restart your Mac. If you have multiple users on the same Mac, be aware
 that this setting only applies to your user account.
 
@@ -69,14 +71,14 @@ that this setting only applies to your user account.
 For a quick test, open a terminal and start Cockatrice with the file on the command line, replacing the path with the
 full location of your file:
 
-```text
+```shell
 QT_LOGGING_CONF=/path/to/qtlogging.ini cockatrice
 ```
 
 If this works and you want it to apply every time you start Cockatrice, add the following line to your `~/.profile`
 file and log in again:
 
-```text
+```shell
 export QT_LOGGING_CONF="/path/to/qtlogging.ini"
 ```
 
@@ -92,7 +94,7 @@ operating system.
 
 If you prefer to capture everything to a file instead, start Cockatrice with the `--debug-output` option:
 
-```text
+```shell
 cockatrice --debug-output
 ```
 

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

@@ -25,22 +25,11 @@ image, so the order matters: URLs at the top of the list are tried first.
 The list can be found in 'Cockatrice → Settings' (or Ctrl + Shift + P by default), on the 'Deck Editor' tab, in the
 'URL Download Priority' section. Make sure 'Download card pictures on the fly' is enabled and that the list contains
 valid URLs. If you suspect the list has been modified or corrupted, press 'Reset Download URLs' to restore the
-defaults:
-
-```text
-https://cards.scryfall.io/large/!prop:side!/!set:uuid_substr_0_1!/!set:uuid_substr_1_1!/!set:uuid!.jpg
-https://api.scryfall.com/cards/!set:uuid!?format=image&face=!prop:side!
-https://api.scryfall.com/cards/multiverse/!set:muid!?format=image
-https://gatherer.wizards.com/Handlers/Image.ashx?multiverseid=!set:muid!&type=card
-https://gatherer.wizards.com/Handlers/Image.ashx?name=!name!&type=card
-```
+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.
 
-\attention The Scryfall templates resolve the exact printing of a card, while the Gatherer templates do not. See
-[Provider Accuracy](#provider-accuracy) below.
-
 # Check Your Local Picture Folder
 
 Before any network request is made, Cockatrice looks for local image files. If a matching file is found on disk it is
@@ -88,7 +77,15 @@ download URLs are remembered; lowering it can help if a URL used to redirect som
 After updating the client, changing the download URLs, moving or deleting local image files, or clearing caches, it is
 recommended to restart Cockatrice so that all changes are fully picked up.
 
-# Enable Picture Loader Logs
+# Check Logs
+
+Before changing any settings, check the existing logs first. Rate limit errors and most download errors are already
+logged at warn level, so you may find the cause without enabling debug mode.
+
+Open 'Help → View Debug Log' and look for error or warning messages related to card picture loading. If you need more
+detail than the default log level provides, see below.
+
+# Enable Picture Loader Debug Logs
 
 If the steps above did not solve the problem, you can turn on a "diagnostics mode" that prints what the picture loader
 is actually doing: which URL it is trying, whether it found or missed a file on disk, whether the download succeeded or