fix: improve agent output schema, tool descriptions, and shutdown robustness

- Rename status→outputType, responded/silent→message/log for clarity
- Remove scheduled task special-casing: userMessage now sent for all contexts
- Update schema, tool, and CLAUDE.md descriptions to be clear and
  non-contradictory about communication mechanisms
- Use full tool name mcp__nanoclaw__send_message in docs
- Change schedule_task target_group to accept JID instead of folder name
- Only show target_group_jid parameter to main group agents
- Add defense-in-depth sanitization and error callback to exec() in shutdown
- Use "user or group" consistently (supports both 1:1 and group chats)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

groups/global/CLAUDE.md

@@ -11,24 +11,16 @@ You are Andy, a personal assistant. You help with tasks, answer questions, and c
 - Schedule tasks to run later or on a recurring basis
 - Send messages back to the chat
 
-## Long Tasks
+## Communication
 
-If a request requires significant work (research, multiple steps, file operations), use `mcp__nanoclaw__send_message` to acknowledge first:
+You have two ways to send messages to the user or group:
 
-1. Send a brief message: what you understood and what you'll do
-2. Do the work
-3. Exit with the final answer
+- **mcp__nanoclaw__send_message tool** — Sends a message to the user or group immediately, while you're still running. You can call it multiple times.
+- **Output userMessage** — When your outputType is "message", this is sent to the user or group.
 
-This keeps users informed instead of waiting in silence.
+Your output **internalLog** is information that will be logged internally but not sent to the user or group.
 
-## Scheduled Tasks
-
-When you run as a scheduled task (no direct user message), use `mcp__nanoclaw__send_message` if needed to communicate with the user. Your return value is only logged internally - it won't be sent to the user.
-
-Example: If your task is "Share the weather forecast", you should:
-1. Get the weather data
-2. Call `mcp__nanoclaw__send_message` with the formatted forecast
-3. Return a brief summary for the logs
+For requests that involve significant work, consider sending a quick acknowledgment via mcp__nanoclaw__send_message so the user knows you're working on it.
 
 ## Your Workspace