ExpressionSimplifier references variables declared in loop body when simplifying the post block

## Description

Hi! I tried to compile the following Solidity code using `solc-latest --optimize --yul-optimizations 'xajs' --bin out.sol`, enabling the custom optimization sequence `xajs`. solc threw an `Invalid assembly/yul code` exception.

```solidity
contract Test {

function g() private returns(bool) {
assembly {
for {
let x := 1
let y := 1
}
iszero(eq(x, 10))
{
x := add(x, y)
}
{ x := add(x, 1) }
}
return true;
}

function f() public returns(bool) {
return g();
}
}
```

Output:
```
Uncaught exception:
/solidity/libyul/AsmAnalysis.cpp(111): Throw in function static solidity::yul::AsmAnalysisInfo solidity::yul::AsmAnalyzer::analyzeStrictAssertCorrect(const solidity::yul::Dialect&, const solidity::yul::Block&, solidity::yul::Object::Structure)
Dynamic exception type: boost::wrapexcept
std::exception::what: Invalid assembly/yul code.
[solidity::util::tag_comment*] = Invalid assembly/yul code.
```

## Environment

- Compiler version: `solc-0.8.25+`

Reproduce the failure with the supplied Solidity contract and the `solc-latest --optimize --yul-optimizations 'xajs'` command. Inspect the ExpressionSimplifier behavior around loop-body variables and the failure reported at `libyul/AsmAnalysis.cpp:111`; done means the example no longer produces invalid assembly/Yul code.

Written by the indexing model from the issue text.