feat: add project termination feature

[dinahmaccodes]

Description

Implemented project termination functionality that allows admins to mark projects as inactive, preventing further operations on completed or invalid projects.

Changes

• Added project_status mapping to track active/terminated state
• Created terminate_project function (admin-only)
• Added is_project_active as an internal helper function
• Implemented protective checks in fund operations
• Emitted ProjectTerminated event when projects are terminated

Tests

Added tests for:

• Default active status for new projects
• Admin-only termination permissions
• Preventing operations on terminated projects
• Event emission on termination
  Error handling for invalid cases

Closes #64
@anonfedora