feat: auto-hide controls in full screen, add subtitle size and outline settings

src/settings/qtpotatosettings.kcfg

@@ -3,6 +3,20 @@
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.kde.org/standards/kcfg/1.0 http://www.kde.org/standards/kcfg/1.0/kcfg.xsd">
   <kcfgfile name="qtpotatorc"/>
+  <group name="Subtitles">
+    <entry name="SubtitleFontSize" type="Int">
+      <label>Font size of plain-text and translated subtitles, in mpv's scaled pixels (mpv's own default is 38)</label>
+      <default>52</default>
+      <min>20</min>
+      <max>150</max>
+    </entry>
+    <entry name="SubtitleOutlineSize" type="Int">
+      <label>Outline width of plain-text and translated subtitles (mpv's own default is 1.65)</label>
+      <default>3</default>
+      <min>0</min>
+      <max>10</max>
+    </entry>
+  </group>
   <group name="Translation">
     <entry name="ApiBaseUrl" type="String">
       <label>Base URL of the OpenAI-compatible API, including the version path (for example …/v1)</label>