Optimize startup: show black overlay first, dim brightness in a background thread; switch to one-folder PyInstaller build (no on-launch extraction)

- black screen now appears immediately (window creation), while the slow
  screen-brightness-control WMI queries (get+set) run in a daemon thread and
  are invisible behind the black overlay
- one-folder COLLECT build removes the ~2-3s one-file archive extraction

Black Screen Dim.spec

@@ -19,8 +19,6 @@ pyz = PYZ(a.pure)
 exe = EXE(
     pyz,
     a.scripts,
-    a.binaries,
-    a.datas,
     [],
     name='Black Screen Dim',
     debug=False,
@@ -37,3 +35,10 @@ exe = EXE(
     entitlements_file=None,
     icon=['icon.ico'],
 )
+
+coll = COLLECT(
+    exe,
+    a.binaries,
+    a.datas,
+    name='Black Screen Dim',
+)