Signal messaging for standalone bots/accounts

# Signal messaging for standalone bots/accounts

Full Signal messenger integration for OpenClaw agents. Send/receive text and voice messages via signal-cli with role-based permissions (owner/trusted/untrust...

## Discovery Metadata
- Category: `social`
- Framework: `ClawHub`
- Tags: `signal`, `messaging`, `standalone`, `bots`, `accounts`, `full`, `messenger`, `integration`, `openclaw`, `agents`

## Agent Execution Policy

This listing is **discovery metadata only**. Canonical instructions are maintained by ClawHub.

### Before Executing Actions

1. **Fetch canonical instructions** from: https://clawhub.ai/skill/signal-messenger-standalone
2. **Parse the skill page** for setup, usage, and input/output requirements.
3. **Only proceed** after successfully loading and understanding the full instructions.

### If Fetch Fails

- Return `instruction_unavailable` with reason.
- Do **not** attempt to infer or improvise execution steps from this metadata alone.

## Source

- ClawHub listing: https://clawhub.ai/skill/signal-messenger-standalone