feat(sidebar): pinned section, dimmed pin glyph, configurable width

Smoke-test round 3 feedback from Jin:

- Sidebar now groups tabs into three sections rendered in this order:
  persistent → pinned TempTabs → unpinned TempTabs. Each TempTab
  section carries its own divider header ("Angepinnt (n)" / "Aktive
  Tells (n)"). Plugin.Config.Tabs order is untouched — only the
  display order changes, so tabI still mirrors the real index and
  LastTab/WantedTab stay consistent.

- The thumbtack glyph overlay on a pinned tab dropped from accent
  colour at full alpha to TextMuted at ~47% alpha. The section header
  is now the primary discoverability cue; the glyph is just a per-tab
  confirmation hint.

- Sidebar width is now a Config field (default 44, range 44-160).
  Slider lives in Theme & Layout under the existing Sidebar-Tab-View
  toggle. The icon button inside each row stretches with the width so
  a widened sidebar doesn't leave the icon floating in dead space.

HellionChat/Resources/HellionStrings.de.resx

@@ -404,6 +404,15 @@
   <data name="PinTab_PinTooltip" xml:space="preserve">
     <value>Angepinnte Tabs überleben Relog und behalten die Bindung an die Tell-Person.</value>
   </data>
+  <data name="PinTab_SectionHeader" xml:space="preserve">
+    <value>Angepinnt</value>
+  </data>
+  <data name="Settings_ThemeAndLayout_SidebarWidth_Name" xml:space="preserve">
+    <value>Sidebar-Breite</value>
+  </data>
+  <data name="Settings_ThemeAndLayout_SidebarWidth_Description" xml:space="preserve">
+    <value>Breite der Tab-Sidebar in Pixeln. Default (44 px) ist Icon-only; breiter machen damit Sektion-Header wie „Aktive Tells (3)" nicht abgeschnitten werden.</value>
+  </data>
 
   <!-- Hellion Chat — Auto-Tell-Tabs (Chat-Einstellungstab) -->
   <data name="ChatLog_AutoTellTabs_Section_Title" xml:space="preserve">