Enhance chatbot conversation engine and add retrieval eval suite

src/App.css

@@ -2216,6 +2216,33 @@
   animation: chatSlideUp 0.22s ease;
 }
 
+.chatbot-page {
+  min-height: 100vh;
+  background:
+    radial-gradient(circle at top, rgba(200, 134, 10, 0.14), transparent 40%),
+    #0a0a0a;
+  padding: 1.25rem;
+}
+
+.chatbot-panel--standalone {
+  position: relative;
+  inset: auto;
+  right: auto;
+  bottom: auto;
+  width: min(780px, 100%);
+  max-height: calc(100vh - 2.5rem);
+  min-height: calc(100vh - 2.5rem);
+  margin: 0 auto;
+}
+
+.chatbot-panel--standalone .chatbot-messages {
+  padding: 1rem 1.1rem;
+}
+
+.chatbot-panel--standalone .chatbot-msg {
+  max-width: 92%;
+}
+
 @keyframes chatSlideUp {
   from { opacity: 0; transform: translateY(12px); }
   to   { opacity: 1; transform: translateY(0); }
@@ -2234,6 +2261,37 @@
   color: #e8c87a;
 }
 
+.chatbot-header-actions {
+  display: flex;
+  align-items: center;
+  gap: 0.55rem;
+}
+
+.chatbot-header-btn {
+  background: rgba(200, 134, 10, 0.12);
+  border: 1px solid rgba(200, 134, 10, 0.28);
+  color: #d9bc7a;
+  border-radius: 999px;
+  padding: 0.28rem 0.72rem;
+  font-size: 0.74rem;
+  font-weight: 600;
+  letter-spacing: 0.03em;
+  cursor: pointer;
+  text-decoration: none;
+  transition: background 0.15s, border-color 0.15s, color 0.15s;
+}
+
+.chatbot-header-btn:hover {
+  background: rgba(200, 134, 10, 0.22);
+  border-color: rgba(200, 134, 10, 0.5);
+  color: #f4ddb0;
+}
+
+.chatbot-header-btn--link {
+  display: inline-flex;
+  align-items: center;
+}
+
 .chatbot-close {
   background: none;
   border: none;
@@ -2264,6 +2322,12 @@
   line-height: 1.5;
 }
 
+.chatbot-msg-suggestions {
+  display: flex;
+  flex-wrap: wrap;
+  gap: 0.55rem;
+  margin-top: 0.85rem;
+}
 .chatbot-msg p {
   margin: 0;
 }
@@ -2344,6 +2408,21 @@
   gap: 0.5rem;
 }
 
+.chatbot-style-select {
+  background: rgba(255, 255, 255, 0.06);
+  border: 1px solid rgba(200, 134, 10, 0.25);
+  color: #d9cba8;
+  border-radius: 0.4rem;
+  padding: 0.45rem 0.5rem;
+  font-size: 0.78rem;
+  outline: none;
+  max-width: 6.8rem;
+}
+
+.chatbot-style-select:focus {
+  border-color: #c8860a;
+}
+
 .chatbot-input {
   flex: 1;
   background: rgba(255, 255, 255, 0.06);