feat: chat speaks as Juan — first person, CV photo avatar, disclaimer tooltip

- Agent prompt rewritten to first person ("I worked at...", "I built...")
- Bot avatar replaced with dni-thumb.jpeg (2.6KB, 56x56 retina)
- Greeting: "Pregúntame lo que quieras sobre mi currículum"
- Underlined "mi currículum" with floating tooltip disclaimer
- Every response ends with cordial email contact invitation
- Background photos now visible in production (random per load)
- Toggle button remains dev-only

static/css/04-interactive/_chat.css

@@ -355,6 +355,27 @@
     background: var(--text-light, #999999);
 }
 
+.chat-avatar-juan {
+    background: none;
+    padding: 0;
+    overflow: hidden;
+}
+
+.chat-avatar-juan img {
+    width: 100%;
+    height: 100%;
+    object-fit: cover;
+    border-radius: 50%;
+}
+
+.chat-disclaimer {
+    display: inline;
+    text-decoration: underline dotted;
+    text-underline-offset: 2px;
+    opacity: 0.7;
+    cursor: help;
+}
+
 .chat-msg {
     padding: 10px 14px;
     border-radius: 16px;