fix: correct i18n SSO translations and fix validation/type issues (#29564)

Signed-off-by: NeatGuyCoding <15627489+NeatGuyCoding@users.noreply.github.com>
Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

api/controllers/service_api/app/completion.py

@@ -61,6 +61,9 @@ class ChatRequestPayload(BaseModel):
     @classmethod
     def normalize_conversation_id(cls, value: str | UUID | None) -> str | None:
         """Allow missing or blank conversation IDs; enforce UUID format when provided."""
+        if isinstance(value, str):
+            value = value.strip()
+
         if not value:
             return None