feat: refactor base64 encoding to use prelude for image handling

Author: lemorage

src/llm/anthropic.rs

@@ -4,7 +4,7 @@ use crate::llm::{
 };
 use anyhow::{Context, Result, bail};
 use async_trait::async_trait;
-use base64::Engine;
+use base64::prelude::*;
 use json5;
 use serde_json::Value;
 
@@ -42,8 +42,7 @@ impl LlmGenerationClient for Client {
 
         // Add image part if present
         if let Some(image_bytes) = &request.image {
-            let base64_image =
-                base64::engine::general_purpose::STANDARD.encode(image_bytes.as_ref());
+            let base64_image = BASE64_STANDARD.encode(image_bytes.as_ref());
             let mime_type = detect_image_mime_type(image_bytes.as_ref())?;
             user_content_parts.push(serde_json::json!({
                 "type": "image",

src/llm/gemini.rs

@@ -4,7 +4,7 @@ use crate::llm::{
     LlmEmbeddingClient, LlmGenerateRequest, LlmGenerateResponse, LlmGenerationClient, OutputFormat,
     ToJsonSchemaOptions, detect_image_mime_type,
 };
-use base64::Engine;
+use base64::prelude::*;
 use phf::phf_map;
 use serde_json::Value;
 use urlencoding::encode;
@@ -78,8 +78,7 @@ impl LlmGenerationClient for Client {
 
         // Add image part if present
         if let Some(image_bytes) = &request.image {
-            let base64_image =
-                base64::engine::general_purpose::STANDARD.encode(image_bytes.as_ref());
+            let base64_image = BASE64_STANDARD.encode(image_bytes.as_ref());
             let mime_type = detect_image_mime_type(image_bytes.as_ref())?;
             user_parts.push(serde_json::json!({
                 "inlineData": {

src/llm/openai.rs

@@ -15,6 +15,7 @@ use async_openai::{
     },
 };
 use async_trait::async_trait;
+use base64::prelude::*;
 use phf::phf_map;
 
 static DEFAULT_EMBEDDING_DIMENSIONS: phf::Map<&str, u32> = phf_map! {
@@ -68,8 +69,7 @@ impl LlmGenerationClient for Client {
         // Add user message
         let user_message_content = match request.image {
             Some(img_bytes) => {
-                use base64::{Engine as _, engine::general_purpose::STANDARD};
-                let base64_image = STANDARD.encode(img_bytes.as_ref());
+                let base64_image = BASE64_STANDARD.encode(img_bytes.as_ref());
                 let mime_type = detect_image_mime_type(img_bytes.as_ref())?;
                 let image_url = format!("data:{};base64,{}", mime_type, base64_image);
                 ChatCompletionRequestUserMessageContent::Array(vec![