- Add new `/api/s2a/profiles` endpoint supporting GET, POST, DELETE operations
- Create `s2a_profiles` database table with fields for API configuration, concurrency, priority, group IDs, and proxy settings
- Implement database methods: `GetS2AProfiles()`, `AddS2AProfile()`, `DeleteS2AProfile()`
- Add S2AProfile struct to database models with JSON serialization support
- Implement profile management UI in S2AConfig page with save, load, and delete functionality
- Add profile list display with ability to apply saved configurations
- Add S2AProfile type definition to frontend types
- Enable users to save and reuse S2A configurations as presets for faster setup
kyx236
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