feat: add agent identity avatars (#1329) (thanks @dlauer)

docs/gateway/configuration.md

@@ -402,13 +402,23 @@ If set, Clawdbot derives defaults (only when you haven’t set them explicitly):
 - `agents.list[].groupChat.mentionPatterns` from the agent’s `identity.name`/`identity.emoji` (so “@Samantha” works in groups across Telegram/Slack/Discord/iMessage/WhatsApp)
 - `identity.avatar` accepts a workspace-relative image path or a remote URL/data URL. Local files must live inside the agent workspace.
 
+`identity.avatar` accepts:
+- Workspace-relative path (must stay within the agent workspace)
+- `http(s)` URL
+- `data:` URI
+
 ```json5
 {
   agents: {
     list: [
       {
         id: "main",
-        identity: { name: "Samantha", theme: "helpful sloth", emoji: "🦥", avatar: "avatars/sam.png" }
+        identity: {
+          name: "Samantha",
+          theme: "helpful sloth",
+          emoji: "🦥",
+          avatar: "avatars/samantha.png"
+        }
       }
     ]
   }