Register custom slash commands via Mattermost REST API at startup,
handle callbacks via HTTP endpoint on the gateway, and clean up
commands on shutdown.
- New modules: slash-commands.ts (API + registration), slash-http.ts
(callback handler), slash-state.ts (shared state bridge)
- Config schema extended with commands.{native,nativeSkills,callbackPath,callbackUrl}
- Uses oc_ prefix for triggers (oc_status, oc_model, etc.) to avoid
conflicts with Mattermost built-in commands
- Opt-in via channels.mattermost.commands.native: true
- Capability nativeCommands: true exposed for command registry
Closesopenclaw/openclaw#16515
Add Mattermost as a supported messaging channel with bot API and WebSocket integration. Includes channel state tracking (tint, summary, details), multi-account support, and delivery target routing. Update documentation and tests to include Mattermost alongside existing channels.
