Fix 1698 (#1720)

* Fix Symbol Pane not updating on external file reversion (#1715)
Trigger symbol refresh when the document is reloaded externally (e.g., via git reset) or reverted, rather than relying solely on internal buffer changes.

* Preferences: Exclude Markdown and YAML from whitespace stripping

This fixes the trailing whitespace stripping behavior on save:
- Excludes Markdown and YAML files where trailing whitespace can be semantically meaningful.
- Adds description/subtext in the settings switch to clarify that it only applies to syntax-highlighted files, except Markdown and YAML.

Fixes #1698

* Preferences: Simplify whitespace stripping setting subtext

---------

Co-authored-by: Jeremy Wootten <jeremywootten@gmail.com>
Co-authored-by: Ryan Kornheisl <ryan@skarva.tech>

Author: 3 people

src/Dialogs/PreferencesDialog.vala

@@ -22,7 +22,11 @@ public class Scratch.Dialogs.Preferences : Granite.Dialog {
         var general_box = new Gtk.Box (VERTICAL, 12);
         general_box.add (new Granite.HeaderLabel (_("General")));
         general_box.add (new SettingSwitch (_("Save files when changed"), "autosave"));
-        general_box.add (new SettingSwitch (_("Strip trailing whitespace on save"), "strip-trailing-on-save"));
+        general_box.add (new SettingSwitch (
+            _("Strip trailing whitespace on save"),
+            "strip-trailing-on-save",
+            _("Except Plain Text, Markdown and YAML")
+        ));
         general_box.add (new SettingSwitch (
             _("Smart cut/copy lines"),
             "smart-cut-copy",

src/Services/Document.vala

@@ -1319,6 +1319,11 @@ namespace Scratch.Services {
                 return;
             }
 
+            var lang_id = source_view.language.id;
+            if (lang_id == "markdown" || lang_id == "yaml") {
+                return;
+            }
+
             var source_buffer = (Gtk.SourceBuffer)source_view.buffer;
             Gtk.TextIter iter;