Gradio API migration, training pipeline, news page, and UI improvements

- Migrate backend from REST API to Gradio @gradio/client for generation
- Fix Gradio parameter alignment (positions 36-49) for reference/cover audio
- Add LoRA training pipeline with dataset upload, preprocessing, and export
- Add News page with dismiss/restore and GitHub star button
- Add localization info icon in Settings language section
- Fix upload audio URL prefix, add missing MIME types
- Add training API routes and Python preprocess script
- Update i18n with news keys for all languages

data/news.json

@@ -0,0 +1,16 @@
+[
+  {
+    "id": "v1-gradio-migration",
+    "date": "2025-02-09",
+    "title": "Switched to Gradio API Backend",
+    "body": "We migrated the backend from REST API to Gradio API for direct communication with ACE-Step. This version is experimental — if you encounter any bugs, please report them or open a PR on our GitHub repo.",
+    "tags": ["backend", "experimental"]
+  },
+  {
+    "id": "v1-training-experimental",
+    "date": "2025-02-09",
+    "title": "LoRA Training (Experimental)",
+    "body": "The training feature is now available but still experimental. You may encounter bugs during dataset building, preprocessing, or training. Bug reports and PRs are welcome!",
+    "tags": ["training", "experimental"]
+  }
+]