This PR implements the fixes requested in #919:

• Added minimum fee of 1 token using a ternary conditional.
• Capped maxLoanAmount to 50% of the pool balance via totalAssets / 2.
• Transitioned to internal accounting (totalAssets) instead of loanToken.balanceOf(address(this)) to prevent rebasing token exploits.
• Added onlyOwner modifier and setPaused(bool) function for emergency pauses.
• Provided the required .contributor.json file.

/claim #919