feat: chat avatars + dark theme fix + text overflow fix

Avatars:
- Robot icon (green circle) before each agent message
- Person icon (dark circle) before each user message
- New .chat-bubble wrapper with flex layout for avatar + message

Dark theme fixes:
- Panel background: #1e1e1e (not pure black)
- Agent bubbles: #2d2d2d with light text (not dark/invisible)
- Input area: #2d2d2d (not black)
- Header stays green (--accent-green) in both themes
- Chips, suggestions consistent with panel background

Text overflow:
- overflow-wrap + word-break on messages
- min-width: 0 prevents flex overflow
- User bubble properly right-aligned with avatar

templates/partials/widgets/chat-widget.html

@@ -28,8 +28,9 @@
     </div>
 
     <div id="chat-messages" class="chat-messages">
-        <div class="chat-message chat-agent">
-            {{if eq .Lang "es"}}¡Hola! Pregúntame lo que quieras sobre este CV.{{else}}Hi! Ask me anything about this CV.{{end}}
+        <div class="chat-bubble chat-bot">
+            <div class="chat-avatar chat-avatar-bot"><iconify-icon icon="mdi:robot-happy-outline"></iconify-icon></div>
+            <div class="chat-message">{{if eq .Lang "es"}}¡Hola! Pregúntame lo que quieras sobre este CV.{{else}}Hi! Ask me anything about this CV.{{end}}</div>
         </div>
     </div>