fix: enforce amountOutMin and final profitability on DEX swaps

[arawrdn]

GM,

Implemented slippage enforcement for all DEX swaps.

Changes:

• Added _minOut(quotedOut, slippageBps) helper.
• Replaced amountOutMin = 0 with quoted minimum output.
• Uses router.getAmountsOut() before each swap.
• Applies configurable slippage in basis points.
• Validates slippageBps <= 10_000.
• Enforces final profitability after execution.

Impact:

• Prevents swaps from accepting unlimited negative slippage.
• Protects against stale quotes, MEV, and price movement.
• Reverts if actual output is below the minimum expected amount.
• Reverts if final balance does not exceed initialBalance + minProfit.

Example:

uint256[] memory amounts = router.getAmountsOut(amountIn, path);
uint256 minOut = _minOut(amounts[amounts.length - 1], slippageBps);

router.swapExactTokensForTokens(
    amountIn,
    minOut,
    path,
    address(this),
    block.timestamp
);

Profit check:

require(finalBalance > initialBalance + minProfit, "not profitable");

Cheers,

[Devilla]

@arawrdn Please create a separate .sol contract file; don't paste the entire code to the README.md file.