AI Translation fails silently on LLM 503 errors — no retry logic
Bug: When any LLM provider (Mistral, OpenAI) returns a 503, DiscourseAi::Translation silently skips the translation with no retry.
Log example:
DiscourseAi::Completions::Endpoints::Mistral: status: 503
{“type”:“unreachable_backend”,“code”:“1100”}
DiscourseAi::Translation: Failed to translate topic X to ru
Root cause: DiscourseAi::Completions::Endpoints has no retry logic for transient server errors. This is not provider-specific — same behavior observed with OpenAI previously.
Expected behavior: Retry with exponential backoff on 503/504 responses before marking translation as failed.
Proposed fix: Add retry logic in DiscourseAi::Completions::Endpoints for all providers uniformly.
This affects any Discourse instance using AI translation with multiple languages.