Improve system project UX and make dependencies a modal

- Hide tag count stat for system projects (show "versions" instead of "artifacts")
- Hide "Latest" tag stat for system projects
- Change "Create/Update Tag" to only show for non-system projects
- Add "View Artifact ID" menu option with modal showing the SHA256 hash
- Move dependencies section to a modal (opened via "View Dependencies" menu)
- Add deps-modal and artifact-id-modal CSS styles

frontend/src/pages/PackagePage.css

@@ -930,3 +930,57 @@ tr:hover .copy-btn {
   padding-top: 16px;
   border-top: 1px solid var(--border-primary);
 }
+
+/* Dependencies Modal */
+.deps-modal {
+  background: var(--bg-secondary);
+  border-radius: var(--radius-lg);
+  width: 90%;
+  max-width: 600px;
+  max-height: 80vh;
+  overflow: hidden;
+  display: flex;
+  flex-direction: column;
+}
+
+.deps-modal .modal-body {
+  overflow-y: auto;
+  flex: 1;
+}
+
+.deps-modal-controls {
+  display: flex;
+  gap: 8px;
+  margin-bottom: 16px;
+}
+
+/* Artifact ID Modal */
+.artifact-id-modal {
+  background: var(--bg-secondary);
+  border-radius: var(--radius-lg);
+  width: 90%;
+  max-width: 500px;
+}
+
+.artifact-id-display {
+  display: flex;
+  align-items: center;
+  gap: 12px;
+  padding: 16px;
+  background: var(--bg-tertiary);
+  border-radius: var(--radius-md);
+  border: 1px solid var(--border-primary);
+}
+
+.artifact-id-display code {
+  font-family: 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;
+  font-size: 0.8125rem;
+  color: var(--text-primary);
+  word-break: break-all;
+  flex: 1;
+}
+
+.artifact-id-display .copy-btn {
+  opacity: 1;
+  flex-shrink: 0;
+}