refactor(MikrotikBackupsManager): enhance diff panel styles for better contrast and visibility

frontend/src/MikrotikBackupsManager.jsx

@@ -53,8 +53,8 @@ const diffPanelStyle = {
   margin: 0,
   padding: '0.5rem 0.75rem',
   borderRadius: 4,
-  backgroundColor: 'var(--tblr-bg-surface, #ffffff)',
-  border: '1px solid var(--tblr-border-color, #e2e8f0)',
+  backgroundColor: 'var(--tblr-code-bg, #0f172a)', // как тёмный code-блок Tabler
+  border: '1px solid rgba(15, 23, 42, 0.9)',
 };
 const diffLineStyle = {
   display: 'block',
@@ -63,13 +63,14 @@ const diffLineStyle = {
   wordBreak: 'break-word',
   padding: '0 4px',
   margin: 0,
+  color: 'var(--tblr-code-color, #e5e7eb)',
 };
 const diffRemovedBg = {
-  background: 'rgba(248, 81, 73, 0.08)',
+  background: 'rgba(248, 81, 73, 0.2)',
   borderLeft: '3px solid rgba(248, 81, 73, 0.9)',
 };
 const diffAddedBg = {
-  background: 'rgba(63, 185, 80, 0.08)',
+  background: 'rgba(63, 185, 80, 0.2)',
   borderLeft: '3px solid rgba(63, 185, 80, 0.9)',
 };