Add AI Enhance toggle for better genre accuracy

When enabled, uses the LLM to enrich genre/style tags into detailed
music descriptions and generate proper BPM, key, and time signature
metadata (CoT features). Fixes genre tags like "pop, rock" producing
ballad-like output by matching Gradio UI default behavior.

- Add enhance toggle in Style of Music card header
- Gate CoT metas/caption/language by enhance OR thinking flag
- Remove unsupported --lm-backend/--lm-model from Python fallback
- Add i18n translations (en/zh/ja/ko) with tooltip

types.ts

@@ -78,6 +78,7 @@ export interface GenerationParams {
   randomSeed: boolean;
   seed: number;
   thinking: boolean;
+  enhance?: boolean;
   audioFormat: 'mp3' | 'flac';
   inferMethod: 'ode' | 'sde';
   shift: number;