refactor(plugin): fabric-register is a script, not a tool

Binding an agent's Fabric API key was an OpenClaw tool; make it a
self-contained Node script installed to ~/.openclaw/bin/fabric-register
instead.

- bin/fabric-register.mjs: no plugin deps; AGENT_ID env wins, else
  --agent-id required; --api-key validated via POST /auth/agent/login;
  on success upserts ~/.openclaw/fabric-identity.json (format matches
  IdentityRegistry). Flags/env for center, identity-file, openclaw-path.
- install.mjs: copy the script to ~/.openclaw/bin (chmod 0755) on
  install, remove on uninstall; Next-steps updated.
- tools.ts: drop the fabric-register tool; ctxGuild error now points to
  the script / static accounts config.
- README updated.

Verified: missing-id -> exit 2; --agent-id and AGENT_ID both bind and
write a valid identity file; bad key -> 401, no write.

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

install.mjs

@@ -10,7 +10,7 @@
  */
 
 import { execSync } from 'child_process';
-import { existsSync, mkdirSync, copyFileSync, readdirSync, rmSync } from 'fs';
+import { existsSync, mkdirSync, copyFileSync, readdirSync, rmSync, chmodSync } from 'fs';
 import { dirname, join, resolve } from 'path';
 import { fileURLToPath } from 'url';
 import { homedir } from 'os';
@@ -109,12 +109,30 @@ function build() {
   ok('compiled -> dist/fabric');
 }
 
+function binTarget(base) {
+  return join(base, 'bin', 'fabric-register');
+}
+
+function installBinScript(base) {
+  const src = join(__dirname, 'bin', 'fabric-register.mjs');
+  const dst = binTarget(base);
+  mkdirSync(dirname(dst), { recursive: true });
+  copyFileSync(src, dst);
+  chmodSync(dst, 0o755);
+  ok(`fabric-register -> ${dst}`);
+}
+
 function clearInstall(base) {
   const dest = join(base, 'plugins', PLUGIN_ID);
   if (existsSync(dest)) {
     rmSync(dest, { recursive: true, force: true });
     ok(`removed ${dest}`);
   }
+  const bin = binTarget(base);
+  if (existsSync(bin)) {
+    rmSync(bin, { force: true });
+    ok(`removed ${bin}`);
+  }
 }
 function cleanupConfig(base) {
   const dest = join(base, 'plugins', PLUGIN_ID);
@@ -149,6 +167,7 @@ function install() {
   ok(`plugin files -> ${dest}`);
   exec('npm install --omit=dev', { cwd: dest, silent: !opt.verbose });
   ok('runtime deps installed');
+  installBinScript(base);
   return { base, dest };
 }
 
@@ -200,8 +219,10 @@ function main() {
     console.log('');
     log('Install complete. Next:', 'blue');
     log('  1. Mint an agent key:  (in Center) node dist/cli.js user apikey --email <agent-email>', 'cyan');
-    log('  2. openclaw gateway restart', 'cyan');
-    log('  3. As an agent, call the fabric-register tool with that key', 'cyan');
+    log('  2. Bind it to an agent (one-time), either:', 'cyan');
+    log('       AGENT_ID=<agent> ~/.openclaw/bin/fabric-register --api-key <fak_…>', 'cyan');
+    log('       (or pass --agent-id <agent>; or set channels.fabric.accounts.<agent>)', 'cyan');
+    log('  3. openclaw gateway restart', 'cyan');
     console.log('');
   } catch (e) {
     log(`\nInstall failed: ${e.message}`, 'red');