Refactor statistics page and enhance logging

- Updated the layout and styling of the statistics page for better responsiveness and visual appeal.
- Introduced a new error page for 404 errors with user-friendly messaging and navigation options.
- Enhanced logging functionality to capture detailed events related to asset uploads, deletions, and HTTP requests.
- Implemented an AssetTracker to manage assets in memory, allowing for efficient tracking and retrieval.
- Improved the API for uploading and retrieving assets, ensuring better error handling and response formatting.
- Added auto-refresh functionality to the statistics page to keep data up-to-date.

data/html/style.css

@@ -3,6 +3,8 @@
   --bg-primary: #1e1e2e;
   --bg-secondary: #1a1a1a;
   --bg-tertiary: #1a1a1a;
+  --bg-glow: rgba(51, 204, 255, 0.08);
+  --bg-glow-strong: rgba(0, 255, 153, 0.07);
   --active-cyan: #33ccff;
   --active-green: #00ff99;
   --inactive-gray: #595959;
@@ -29,6 +31,11 @@ body {
   padding: 20px;
   padding-bottom: 140px;
   background-color: var(--bg-tertiary);
+  background-image:
+    radial-gradient(1200px 800px at 10% -20%, var(--bg-glow), transparent 60%),
+    radial-gradient(900px 700px at 110% 0%, var(--bg-glow-strong), transparent 55%),
+    linear-gradient(180deg, rgba(30, 30, 46, 0.35), rgba(26, 26, 26, 0.85));
+  background-attachment: fixed;
   color: var(--text-primary);
   display: flex;
   flex-direction: column;
@@ -512,6 +519,55 @@ body.view-page {
   text-align: center;
 }
 
+/* Error page styles */
+.error-page .content-area {
+  min-height: 320px;
+}
+
+.error-content {
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  gap: 12px;
+  text-align: center;
+  padding: 10px;
+}
+
+.error-code {
+  font-size: 3.2em;
+  font-weight: bold;
+  color: var(--accent-cyan);
+  text-shadow: 0 0 12px rgba(51, 204, 255, 0.4);
+}
+
+.error-message {
+  color: var(--text-secondary);
+  font-size: 1.05em;
+  margin: 0;
+}
+
+.error-actions {
+  display: flex;
+  gap: 12px;
+  flex-wrap: wrap;
+  justify-content: center;
+  align-items: center;
+}
+
+.action-btn {
+  text-decoration: none;
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  text-align: center;
+  min-width: 140px;
+}
+
+.error-actions .upload-btn,
+.error-actions .reset-btn {
+  flex: 0 0 auto;
+}
+
 @keyframes pulse {
 
   0%,
@@ -560,4 +616,4 @@ body.view-page {
 
 .text-content-view::-webkit-scrollbar-thumb:hover {
   background: var(--border-hover);
-}
+}