fix(ci): attach cause when rethrowing bridge-restore failure (v0.18.1-beta)

The backend Lint job failed on the new createBond error path: ESLint's
preserve-caught-error rule (in effect since the eslint 10.7 bump) requires a
rethrown error to carry the original. Pass `{ cause: err }`, which also makes the
underlying RouterOS failure visible in the error chain instead of only inside the
message string.

No behavior change beyond the richer error. Verified with the exact CI commands:
`npm run lint` and `npm run build` both exit 0, 133 backend tests pass, and the
redeployed build still guards correctly (guarded change commits, disabling the
management service is refused with 409).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/package.json

@@ -1,6 +1,6 @@
 {
   "name": "mikrotik-manager-backend",
-  "version": "0.18.0-beta",
+  "version": "0.18.1-beta",
   "description": "Mikrotik Network Management Platform - Backend API",
   "main": "dist/index.js",
   "scripts": {

backend/src/services/mikrotik/DeviceCollector.ts

@@ -2773,7 +2773,8 @@ export class DeviceCollector {
         throw new Error(
           `Bond '${name}' was created, but adding it to bridge '${originalBridge}' failed: ` +
           `${(err as Error).message}. The member ports (${slaves.join(', ')}) are no longer bridged ` +
-          `and may not forward traffic — check the device.`
+          `and may not forward traffic — check the device.`,
+          { cause: err }
         );
       }
     }