#44 Issue 44: [Security] Minimum Balance Fail-Safe


Description:
Ensure the contract always maintains a "Buffer" of XLM to pay for its own ledger rent (TTL bumps) so it never becomes archived while holding active grants.
Acceptance Criteria:

[ ] Implement reserve_rent_funds() during contract initialization.

[ ] Prevent the Admin from withdrawing the last ~5 XLM of the contract's own balance.
Labels: security, maintenance