feat: add agent avatar support (#1329) (thanks @dlauer)

docs/gateway/configuration.md

@@ -400,12 +400,16 @@ Optional per-agent identity used for defaults and UX. This is written by the mac
 If set, Clawdbot derives defaults (only when you haven’t set them explicitly):
 - `messages.ackReaction` from the **active agent**’s `identity.emoji` (falls back to 👀)
 - `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.
 
 ```json5
 {
   agents: {
     list: [
-      { id: "main", identity: { name: "Samantha", theme: "helpful sloth", emoji: "🦥" } }
+      {
+        id: "main",
+        identity: { name: "Samantha", theme: "helpful sloth", emoji: "🦥", avatar: "avatars/sam.png" }
+      }
     ]
   }
 }