refactor(core): replace JSON-based pipeline with MySQL database

This commit introduces a major architectural overhaul, migrating the data backend from a flat JSON
file to a relational MySQL database.

- Replaced multiple scraping scripts with a unified `main.py` that handles crawling, parsing, and
database synchronization.
- Introduced `mysql_helper.py` for robust database interaction with a connection pool.
- Added `queries.sql` defining the new database schema for assets, categories, tags, and changelogs.
- Removed all obsolete frontend code (v1, v2) and old scraping scripts.

This change provides a more scalable and maintainable foundation for managing asset data.

.gitignore

@@ -49,4 +49,7 @@ pnpm-debug.log*
 # 压缩包等导出文件
 *.zip
 *.tar.gz
-*.rar
+*.rar
+
+# Output
+media