[FEATURE]: Implement Retry Queue for Failed Panel Heartbeats

[msikorski26]

Summary
Add a local queue mechanism to the worker so it can retry sending heartbeat/status updates to the panel when the connection fails (e.g., panel temporarily unavailable). This ensures no data loss during outages.

Motivation
Currently, if the panel is down or unreachable, heartbeats are silently dropped. A retry queue would make the worker more resilient:

• Buffers updates locally (e.g., in-memory or SQLite).
• Retries on next successful connection.
• Prevents data gaps in monitoring history.

Proposed Implementation

1. Queue Storage: Use a lightweight queue (e.g., in-memory array or persistent SQLite) to store failed payloads with timestamps.
2. Retry Logic:
   • On send failure: Enqueue payload with retry count (max 5-10).
   • On successful connection: Flush queue oldest-first.
   • Exponential backoff for retries (e.g., 1s → 5s → 30s).
3. Config Options:

   Option	Type	Default	Description
   retryQueue.enabled	boolean	true	Enable/disable queue
   retryQueue.maxSize	number	1000	Max queued items
   retryQueue.persistence	string	'memory'	'memory' | 'sqlite'
   retryQueue.maxRetries	number	10	Per-item retry limit

Example Flow

Worker detects downtime → Enqueue: {timestamp: now, status: {...}, retry: 1}
Panel back online → Retry queue → Send batched → Clear on success