Add drag-and-drop upload component with chunked uploads and offline support

frontend/src/pages/PackagePage.css

@@ -127,6 +127,58 @@ h2 {
   font-size: 0.75rem;
 }
 
+/* Download by Artifact ID Section */
+.download-by-id-section {
+  margin-top: 32px;
+  background: var(--bg-secondary);
+}
+
+.download-by-id-section h3 {
+  margin-bottom: 12px;
+  color: var(--text-primary);
+  font-size: 1rem;
+  font-weight: 600;
+}
+
+.download-by-id-form {
+  display: flex;
+  gap: 12px;
+  align-items: center;
+}
+
+.artifact-id-input {
+  flex: 1;
+  padding: 10px 16px;
+  background: var(--bg-tertiary);
+  border: 1px solid var(--border-primary);
+  border-radius: var(--radius-md);
+  font-family: 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;
+  font-size: 0.8125rem;
+  color: var(--text-primary);
+}
+
+.artifact-id-input::placeholder {
+  color: var(--text-muted);
+}
+
+.artifact-id-input:focus {
+  outline: none;
+  border-color: var(--accent-primary);
+}
+
+.btn-disabled {
+  opacity: 0.5;
+  cursor: not-allowed;
+  pointer-events: none;
+}
+
+.validation-hint {
+  margin-top: 8px;
+  margin-bottom: 0;
+  font-size: 0.75rem;
+  color: var(--warning-color, #f59e0b);
+}
+
 /* Usage Section */
 .usage-section {
   margin-top: 32px;