feat(plugin): sync OpenClaw slash-command catalog to Fabric

- command-sync.ts: buildFabricCommandSpecs(cfg) reads OpenClaw native
  command specs via openclaw/plugin-sdk/native-command-registry
  (listNativeCommandSpecsForConfig + findCommandByNativeName), resolves
  dynamic arg choices to a static snapshot (resolveCommandArgChoices) —
  same data Discord registers as slash commands.
- syncFabricCommands(): on gateway_start, after inbound starts, PUT the
  catalog to each connected guild (FabricClient.syncCommands ->
  PUT /api/commands; idempotent, one per guild).
- Fabric stays a TEXT-command surface (no nativeCommands capability):
  execution still flows as a /<cmd> message into OpenClaw's command
  system; this catalog only drives frontend autocomplete.

Verified: 41 specs built (args/choices incl. dynamic), synced to
test-guild1, GET /api/commands round-trips count=41.

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

index.ts

@@ -11,6 +11,7 @@ import { listEnabledFabricAccounts } from './src/accounts.js';
 import { registerFabricTools } from './src/tools.js';
 import { FabricClient } from './src/fabric-client.js';
 import { IdentityRegistry } from './src/identity.js';
+import { syncFabricCommands } from './src/command-sync.js';
 import path from 'node:path';
 import os from 'node:os';
 
@@ -82,6 +83,7 @@ export default defineChannelPluginEntry({
       );
       void inbound.start();
       api.logger.info(`fabric: inbound started for ${accounts.length} account(s)`);
+      void syncFabricCommands(client, cfg, accounts, api.logger);
     });
 
     api.on('gateway_stop', () => {