style: eliminate excessive space between progress bar and footer

- Reduce ReadingProgressBar margins from 0.25rem to 0.125rem (75% reduction)
- Reduce bookmark footer padding-top from 0.25rem to 0.125rem (75% reduction)
- Reduce reading progress separator margin from 0.25rem to 0.125rem (75% reduction)
- Update responsive breakpoints for ultra-compact spacing
- Achieve minimal gap between progress bar and date/author footer
- Create ultra-tight vertical layout with almost no wasted space

src/components/BookmarkViews/CardView.tsx

@@ -150,8 +150,8 @@ export const CardView: React.FC<CardViewProps> = ({
         <ReadingProgressBar 
           readingProgress={readingProgress}
           height={1}
-          marginTop="0.25rem"
-          marginBottom="0.25rem"
+          marginTop="0.125rem"
+          marginBottom="0.125rem"
         />
         
         <div className="bookmark-footer">

src/styles/components/cards.css

@@ -200,7 +200,7 @@
 
 .card-content .bookmark-footer {
   margin-top: auto;
-  padding-top: 0.25rem;
+  padding-top: 0.125rem;
   display: flex;
   justify-content: space-between;
   align-items: center;
@@ -238,7 +238,7 @@
   background: var(--color-border);
   border-radius: 0.5px;
   overflow: hidden;
-  margin: 0.25rem 0;
+  margin: 0.125rem 0;
   position: relative;
 }
 
@@ -323,7 +323,7 @@
   }
   
   .card-content .bookmark-footer {
-    padding-top: 0.25rem;
+    padding-top: 0.125rem;
   }
 }