style(ui): conflict dialog in Prism dark palette

Same Steam-Cloud-Conflict layout (header glyph + uppercase title +
two card-buttons + Cancel) but recolored to Prism's palette:

  background       #313131 (Prism Window)
  cards            #2a2a2a (Prism AlternateBase)
  card hover       #383838 + #96db59 border (Prism Highlight green)
  cancel button    #303030 + #96db59 border on hover

Warning glyph keeps the light circle (#d6dde6) for high contrast
against the dark surface — gives the same 'pay attention' weight
without forcing a different theme just for one dialog.

cloud_sync/ui_qt.py

@@ -279,7 +279,7 @@ def prompt_login_qt() -> str | None:
 
 
 _CONFLICT_QSS = """
-QDialog { background: #1b2838; }
+QDialog { background: #313131; }
 QLabel#title {
     color: white;
     font-size: 20pt;
@@ -287,7 +287,7 @@ QLabel#title {
     letter-spacing: 2px;
 }
 QLabel#warning {
-    color: #1b2838;
+    color: #313131;
     background: #d6dde6;
     border-radius: 16px;
     font-size: 18pt;
@@ -299,21 +299,21 @@ QLabel#warning {
     max-height: 32px;
 }
 QLabel#body {
-    color: #a9b3bf;
+    color: #c8c8c8;
     font-size: 10pt;
 }
 QLabel#note {
-    color: #7d8a99;
+    color: #8a8a8a;
     font-size: 9pt;
 }
 QFrame#card {
-    background: #2a3f5a;
+    background: #2a2a2a;
     border: 1px solid transparent;
     border-radius: 4px;
 }
 QFrame#card:hover {
-    background: #34507a;
-    border: 1px solid #5b8fc7;
+    background: #383838;
+    border: 1px solid #96db59;
 }
 QLabel#cardTitle {
     color: white;
@@ -322,7 +322,7 @@ QLabel#cardTitle {
     background: transparent;
 }
 QLabel#cardSubtitle {
-    color: #a9b3bf;
+    color: #b8b8b8;
     font-size: 9pt;
     background: transparent;
 }
@@ -332,15 +332,15 @@ QLabel#cardIcon {
     background: transparent;
 }
 QPushButton#cancel {
-    background: #2a475e;
+    background: #303030;
     color: white;
-    border: 1px solid #4a6580;
+    border: 1px solid #4a4a4a;
     border-radius: 2px;
     padding: 8px 24px;
     font-size: 10pt;
 }
-QPushButton#cancel:hover { background: #355d7d; }
-QPushButton#cancel:pressed { background: #1f3548; }
+QPushButton#cancel:hover { background: #3a3a3a; border-color: #96db59; }
+QPushButton#cancel:pressed { background: #222222; }
 """