Run FastEmbed inference on spawn_blocking, propagate Surreal take failures, add AppError::internal and typed ingest/embedding parse errors, and take owned file lists in ingestion payload construction.
- Fix err-lowercase-msg: normalize all #[error(...)] display strings to lowercase (AppError, FileError, ApiErr) and update affected tests - Fix err-doc-errors: add # Errors sections to 25+ fallible public functions across db.rs, store.rs, embedding.rs, indexes.rs, ingestion_task.rs, and ingest_limits.rs
Per Stark