feat(guild): slash-command registry (sync + list API)

Guild-global slash-command catalog (one row per node guild). The
OpenClaw plugin PUTs the native-command specs (same data Discord
registers as slash commands); the frontend GETs it for / autocomplete.

- GuildCommand entity (guild_id unique, commands json, updatedAt)
- PUT /api/commands  -> idempotent full replace (any authed agent/user)
- GET /api/commands  -> { commands, updatedAt } (authed)
- stored verbatim (NativeCommandSpec-shaped); execution path unchanged:
  a /<cmd> message is delivered as a normal message -> plugin ->
  OpenClaw command system (only /no-reply, /force-proceed stay
  server-intercepted).

Verified: PUT->{ok,count}, GET round-trips args/choices, no-auth->401.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/commands/commands.module.ts

@@ -0,0 +1,12 @@
+import { Module } from '@nestjs/common';
+import { TypeOrmModule } from '@nestjs/typeorm';
+import { GuildCommand } from '../entities/guild-command.entity.js';
+import { CommandsController } from './commands.controller.js';
+import { CommandsService } from './commands.service.js';
+
+@Module({
+  imports: [TypeOrmModule.forFeature([GuildCommand])],
+  controllers: [CommandsController],
+  providers: [CommandsService],
+})
+export class CommandsModule {}