feat(dashboard): add npm version update notification

- Add /api/version-check endpoint to check npm registry for updates
- Create version-check.js component with update banner UI
- Add CSS styles for version update banner
- Fix hook manager button event handling (use e.currentTarget)
- Bump version to 6.1.2

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

ccw/src/templates/dashboard-css/01-base.css

@@ -159,3 +159,133 @@ body {
   display: block;
 }
 
+
+/* ===================================
+   Version Update Banner
+   =================================== */
+
+.version-update-banner {
+  position: sticky;
+  top: 0;
+  z-index: 100;
+  background: linear-gradient(135deg, hsl(var(--primary) / 0.1), hsl(var(--accent) / 0.1));
+  border-bottom: 1px solid hsl(var(--primary) / 0.3);
+  padding: 0.75rem 1rem;
+  transform: translateY(-100%);
+  opacity: 0;
+  transition: transform 0.3s ease, opacity 0.3s ease;
+}
+
+.version-update-banner.show {
+  transform: translateY(0);
+  opacity: 1;
+}
+
+.version-banner-content {
+  display: flex;
+  align-items: center;
+  gap: 0.75rem;
+  max-width: 1400px;
+  margin: 0 auto;
+  flex-wrap: wrap;
+}
+
+.version-banner-icon {
+  font-size: 1.25rem;
+}
+
+.version-banner-text {
+  flex: 1;
+  font-size: 0.875rem;
+  color: hsl(var(--foreground));
+}
+
+.version-banner-text code {
+  background: hsl(var(--muted));
+  padding: 0.125rem 0.375rem;
+  border-radius: 0.25rem;
+  font-family: var(--font-mono);
+  font-size: 0.8125rem;
+}
+
+.version-banner-btn {
+  display: inline-flex;
+  align-items: center;
+  gap: 0.375rem;
+  padding: 0.375rem 0.75rem;
+  font-size: 0.8125rem;
+  font-weight: 500;
+  color: hsl(var(--primary-foreground));
+  background: hsl(var(--primary));
+  border: none;
+  border-radius: 0.375rem;
+  cursor: pointer;
+  transition: background 0.2s, transform 0.1s;
+}
+
+.version-banner-btn:hover {
+  background: hsl(var(--primary) / 0.9);
+  transform: translateY(-1px);
+}
+
+.version-banner-btn:active {
+  transform: translateY(0);
+}
+
+.version-banner-btn.secondary {
+  background: hsl(var(--secondary));
+  color: hsl(var(--secondary-foreground));
+}
+
+.version-banner-btn.secondary:hover {
+  background: hsl(var(--secondary) / 0.8);
+}
+
+.version-banner-close {
+  width: 1.5rem;
+  height: 1.5rem;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  font-size: 1.25rem;
+  color: hsl(var(--muted-foreground));
+  background: transparent;
+  border: none;
+  border-radius: 0.25rem;
+  cursor: pointer;
+  transition: background 0.2s, color 0.2s;
+  margin-left: auto;
+}
+
+.version-banner-close:hover {
+  background: hsl(var(--destructive) / 0.1);
+  color: hsl(var(--destructive));
+}
+
+/* Mobile responsiveness for banner */
+@media (max-width: 640px) {
+  .version-banner-content {
+    gap: 0.5rem;
+  }
+
+  .version-banner-text {
+    width: 100%;
+    order: -1;
+  }
+
+  .version-banner-btn {
+    flex: 1;
+    justify-content: center;
+  }
+
+  .version-banner-close {
+    position: absolute;
+    top: 0.5rem;
+    right: 0.5rem;
+  }
+
+  .version-update-banner {
+    position: relative;
+    padding-right: 2.5rem;
+  }
+}