Add splicing module and related tests

- Add src/splicing/ module with scaffold_prep, fragment_prep, and engine
- Add tylosin_splicer.py entry script
- Add unit tests for splicing components

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

scripts/tylosin_splicer.py

@@ -0,0 +1,10 @@
+#!/usr/bin/env python
+"""
+Tylosin Splicing System - Main Entry Point
+"""
+
+def main():
+    print("Hello from Tylosin Splicer")
+
+if __name__ == "__main__":
+    main()