fix: internationalize hardcoded strings in Jina embedder

- Replace hardcoded "Base64/binary embeddings are not supported" with t("embeddings:unsupportedEmbeddingFormat")
- Replace hardcoded "Unknown error" with t("embeddings:unknownError")
- Add "unsupportedEmbeddingFormat" translation key to all supported languages
- Add missing "jinaConfigMissing" translation key to backend embeddings.json files

This fixes hardcoded strings that were found during translation review of the Jina embedder implementation.

Author: roomote

src/i18n/locales/ca/embeddings.json

@@ -48,6 +48,7 @@
 		"geminiConfigMissing": "Gemini configuration missing for embedder creation",
 		"mistralConfigMissing": "Mistral configuration missing for embedder creation",
 		"jinaConfigMissing": "Jina configuration missing for embedder creation",
+		"unsupportedEmbeddingFormat": "Base64/binary embeddings are not supported",
 		"invalidEmbedderType": "Invalid embedder type configured: {{embedderProvider}}",
 		"vectorDimensionNotDeterminedOpenAiCompatible": "Could not determine vector dimension for model '{{modelId}}' with provider '{{provider}}'. Please ensure the 'Embedding Dimension' is correctly set in the OpenAI-Compatible provider settings.",
 		"vectorDimensionNotDetermined": "Could not determine vector dimension for model '{{modelId}}' with provider '{{provider}}'. Check model profiles or configuration.",