Feature: Portal system — entry points to other worlds (#5) (#43)

Co-authored-by: Google Gemini <gemini@hermes.local>
Co-committed-by: Google Gemini <gemini@hermes.local>

style.css

@@ -221,6 +221,127 @@ canvas#nexus-canvas {
   letter-spacing: 0.05em;
 }
 
+/* Portal Hint */
+.portal-hint {
+  position: absolute;
+  top: 50%;
+  left: 50%;
+  transform: translate(-50%, 100px);
+  display: flex;
+  align-items: center;
+  gap: var(--space-2);
+  background: rgba(0, 0, 0, 0.8);
+  padding: var(--space-2) var(--space-4);
+  border: 1px solid var(--color-primary);
+  border-radius: 4px;
+  animation: hint-float 2s ease-in-out infinite;
+}
+@keyframes hint-float {
+  0%, 100% { transform: translate(-50%, 100px); }
+  50% { transform: translate(-50%, 90px); }
+}
+.portal-hint-key {
+  background: var(--color-primary);
+  color: var(--color-bg);
+  font-weight: 700;
+  padding: 2px 8px;
+  border-radius: 2px;
+}
+.portal-hint-text {
+  font-size: var(--text-sm);
+  font-weight: 500;
+  letter-spacing: 0.05em;
+}
+#portal-hint-name {
+  color: var(--color-primary);
+  font-weight: 700;
+}
+
+/* Portal Activation Overlay */
+.portal-overlay {
+  position: fixed;
+  inset: 0;
+  background: rgba(5, 5, 16, 0.95);
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  pointer-events: auto;
+  z-index: 1000;
+}
+.portal-overlay-content {
+  width: 100%;
+  max-width: 500px;
+  text-align: center;
+  padding: var(--space-8);
+}
+.portal-overlay-header {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  gap: var(--space-3);
+  margin-bottom: var(--space-4);
+}
+.portal-overlay-status {
+  width: 12px;
+  height: 12px;
+  border-radius: 50%;
+  background: var(--color-primary);
+  box-shadow: 0 0 10px var(--color-primary);
+}
+.portal-overlay-title {
+  font-family: var(--font-display);
+  font-size: var(--text-sm);
+  letter-spacing: 0.2em;
+  color: var(--color-primary);
+}
+.portal-overlay-content h2 {
+  font-family: var(--font-display);
+  font-size: var(--text-2xl);
+  margin-bottom: var(--space-4);
+  letter-spacing: 0.1em;
+}
+.portal-overlay-content p {
+  color: var(--color-text-muted);
+  font-size: var(--text-base);
+  line-height: 1.6;
+  margin-bottom: var(--space-8);
+}
+.portal-redirect-box {
+  border: 1px solid var(--color-primary-dim);
+  padding: var(--space-6);
+  border-radius: var(--panel-radius);
+}
+.portal-redirect-label {
+  font-size: var(--text-xs);
+  letter-spacing: 0.2em;
+  margin-bottom: var(--space-2);
+}
+.portal-redirect-timer {
+  font-family: var(--font-display);
+  font-size: 48px;
+  font-weight: 700;
+  color: var(--color-primary);
+}
+.portal-error-box {
+  border: 1px solid var(--color-danger);
+  padding: var(--space-6);
+  border-radius: var(--panel-radius);
+}
+.portal-error-msg {
+  color: var(--color-danger);
+  font-weight: 700;
+  margin-bottom: var(--space-4);
+}
+.portal-close-btn {
+  background: var(--color-danger);
+  color: white;
+  border: none;
+  padding: var(--space-2) var(--space-6);
+  border-radius: 4px;
+  font-family: var(--font-display);
+  cursor: pointer;
+}
+
 /* === CHAT PANEL === */
 .chat-panel {
   position: absolute;