Fix: resolve modal confirm action for delete; prevent 500 on dependent entities (Closes #6)
Implement a functional delete confirmation modal on Scientific Programmes, Grant Holders, and Project Calls pages. Prevent server error by handling deletions when dependencies exist, returning a user-facing message via Flash Attribute
Changes:
- Add confirm modal and wire up delete actions on listed pages.
- Add guard to deletion flow to avoid 500 when entity has dependencies; surface error message.
Closes #6