Patch: robust Pinksense/Mixin HTTP layer

Changed files:
- mixin_api_iranskmei.php
- config_iranskmei.php

What changed:
- Added multi-round retry for destination API calls.
- Added retry handling for temporary DNS/cURL errors like: Could not resolve host: pinksense.ir
- Added process-level host IP cache using CURLOPT_RESOLVE after the first successful DNS lookup.
- Added request throttling to avoid hammering the destination DNS/API.
- Added longer connect/request timeout settings.
- Added clearer trace logs: MIXIN_HTTP_RETRY, MIXIN_HTTP_ROUND_SLEEP, MIXIN_RESOLVE_CACHE.

Important:
- This patch does not add local save logic.
- It only makes the destination GET/POST/PATCH layer resilient.