Vendor helgoboss/helgobox (ReaLearn) as basis for custom UI fork

Stripped upstream git history; starting point for replacing the native
SWELL/Win32 mapping UI with something more suited to bulk editing.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

plugin-reaper-realearn/doc/playtime/modules/ROOT/pages/user-interface/dialogs/settings-dialog.adoc

@@ -0,0 +1,31 @@
+= Settings dialog
+
+This dialog opens when pressing the xref:helgobox:ROOT:app/user-interface/title-bar.adoc#title-bar-settings[] button in the title bar and navigating to the Playtime section.
+
+image::generated/screenshots/main/settings.png[]
+
+== Appearance
+
+include::partial$generated/elements/settings/show-control-unit-frames.adoc[]
+
+See xref:further-concepts/matrix.adoc#control-unit-frame[].
+
+include::partial$generated/elements/settings/show-column-numbers.adoc[]
+
+Disabling this will give you more vertical space, but also hides the shortcut buttons such as xref:user-interface/matrix-area.adoc#column-cell-exclusive-mode[]. In that case, you can still change those things in the xref:user-interface/inspector/column.adoc[].
+
+include::partial$generated/elements/settings/show-clip-activity.adoc[]
+include::partial$generated/elements/settings/show-cell-selection-as-crosshair.adoc[]
+include::partial$generated/elements/settings/show-hypothetical-play-cursor.adoc[]
+include::partial$generated/elements/settings/cell-color-position.adoc[]
+include::partial$generated/elements/settings/cell-progress-position.adoc[]
+
+include::partial$generated/elements/settings/cell-width.adoc[]
+
+include::partial$generated/elements/settings/cell-height.adoc[]
+
+In addition, you might be interested in the xref:helgobox::app/user-interface/settings-dialog.adoc#settings-overall-size[] setting, located in the general appearance section.
+
+== Engine
+
+include::partial$generated/elements/settings/tempo-latency.adoc[]