feat: improve BlueBubbles message action error handling and enhance channel action descriptions

src/agents/pi-embedded-runner/system-prompt.ts

@@ -32,6 +32,8 @@ export function buildEmbeddedSystemPrompt(params: {
     provider?: string;
     capabilities?: string[];
     channel?: string;
+    /** Supported message actions for the current channel (e.g., react, edit, unsend) */
+    channelActions?: string[];
   };
   sandboxInfo?: EmbeddedSandboxInfo;
   tools: AgentTool[];