Add Spotify integration, Next button navigation, and UI improvements

- Added Spotify links to all album cards with official green styling
- Implemented Next Album button for sequential navigation (albums 1-499)
- Fixed jump-to-rank to scroll to album card top instead of centering
- Moved share button to same row as album status for better layout
- Improved mobile UI: fixed theme selector overlap, full-width filter controls
- Grouped sort dropdown with reverse button for logical organization
- Updated README with new features and Spotify integration details
- Enhanced vertical alignment of status badges and share buttons
- Refined button sizing and spacing for consistent appearance

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

styles.css

@@ -305,6 +305,12 @@ body {
     flex-wrap: wrap;
 }
 
+.sort-controls {
+    display: flex;
+    gap: 0.5rem;
+    align-items: center;
+}
+
 .filter-select {
     padding: 0.75rem 1rem;
     border: 2px solid #e1e5e9;
@@ -570,25 +576,27 @@ body {
     border-radius: 8px;
 }
 
+.album-status-row {
+    display: flex;
+    justify-content: space-between;
+    align-items: center;
+    gap: 1rem;
+}
+
 .album-share {
-    position: absolute;
-    top: 1rem;
-    right: 1rem;
     background: var(--primary-color);
     color: var(--text-light);
     border: none;
     border-radius: 50%;
-    width: 36px;
-    height: 36px;
+    width: 32px;
+    height: 32px;
     display: flex;
     align-items: center;
     justify-content: center;
     cursor: pointer;
-    font-size: 1rem;
+    font-size: 0.875rem;
     transition: all 0.3s ease;
-    opacity: 0;
-    transform: scale(0.8);
-    backdrop-filter: blur(10px);
+    flex-shrink: 0;
     box-shadow: 0 2px 8px var(--shadow-color);
 }
 
@@ -596,11 +604,6 @@ body {
     color: var(--text-light);
 }
 
-.album-card:hover .album-share {
-    opacity: 1;
-    transform: scale(1);
-}
-
 .album-share:hover {
     background: var(--secondary-color);
     transform: scale(1.1);
@@ -612,7 +615,6 @@ body {
 
 .album-share.copied {
     background: var(--secondary-color);
-    opacity: 1;
 }
 
 .album-card:hover {
@@ -671,7 +673,6 @@ body {
     border-radius: 20px;
     font-size: 0.8rem;
     font-weight: 500;
-    align-self: flex-start;
 }
 
 .status-new {
@@ -729,6 +730,13 @@ body {
     text-align: center;
     padding-top: 1rem;
     border-top: 1px solid #eee;
+    display: flex;
+    flex-direction: column;
+    gap: 0.75rem;
+    align-items: center;
+}
+
+.album-links-row {
     display: flex;
     gap: 1rem;
     justify-content: center;
@@ -807,6 +815,11 @@ body {
     font-family: inherit;
 }
 
+.next-album-link.next-album-link-wide {
+    width: 100%;
+    max-width: 300px;
+}
+
 .next-album-link:hover {
     background: var(--primary-color);
     color: var(--text-light);
@@ -864,6 +877,10 @@ body {
 
 /* Responsive design */
 @media (max-width: 768px) {
+    .header {
+        padding-bottom: 2rem; /* Reduced padding */
+    }
+    
     .supertitle {
         font-size: 1.2rem;
     }
@@ -874,11 +891,12 @@ body {
     
     .subtitle {
         font-size: 1rem;
+        margin-bottom: 0.5rem;
     }
     
     .header-theme-selector {
-        bottom: 0.5rem;
-        right: 0.5rem;
+        position: static;
+        margin-top: 1rem;
     }
     
     .theme-select-header {
@@ -897,11 +915,27 @@ body {
     }
     
     .filters {
-        justify-content: center;
+        flex-direction: column;
+        width: 100%;
+    }
+    
+    .sort-controls {
+        width: 100%;
+        display: grid;
+        grid-template-columns: 1fr auto;
+        gap: 0.5rem;
+    }
+    
+    .filter-select {
+        width: 100%;
+    }
+    
+    .sort-controls .filter-select {
+        width: auto;
     }
     
     .reverse-button {
-        min-width: auto;
+        width: auto;
         padding: 0.75rem;
     }
     
@@ -922,6 +956,11 @@ body {
     
     .theme-selector {
         margin-left: 0;
+        width: 100%;
+    }
+    
+    .theme-select {
+        width: 100%;
     }
     
     .album-card {
@@ -945,9 +984,15 @@ body {
         font-size: 5rem;
     }
     
-    .album-share {
-        opacity: 1;
-        transform: scale(1);
+    .album-status-row {
+        width: 100%;
+        display: flex;
+        justify-content: space-between;
+        align-items: center;
+    }
+    
+    .album-status {
+        margin-right: auto;
     }
     
     .stats {