ICE in `TypeChecker::endVisit(BinaryOperation)` when duplicate `using for` operator bindings include a self-referential call

The compiler panics with `Solidity assertion failed` in [`libsolidity/analysis/TypeChecker.cpp:1706`](https://github.com/ethereum/solidity/blob/9be66192f9db40e5a43f71fc78e06b2f35e9ccdd/libsolidity/analysis/TypeChecker.cpp#L1706) when two functions are bound to the same operator via `using for` and one of them uses that operator in its own body.

MRE:
```solidity
type T is int256;
function sub(T a, T b) pure returns (T) {}
function add(T a, T b) pure returns (T) { T c = a + b; }
using {sub as +, add as +} for T global;
```

Reproduce: save as `mre.sol`, run `solc --bin mre.sol`.

Output:
```
Internal compiler error:
/solidity/libsolidity/analysis/TypeChecker.cpp(1706): Throw in function virtual void solidity::frontend::TypeChecker::endVisit(const solidity::frontend::BinaryOperation&)
Dynamic exception type: boost::wrapexcept
std::exception::what: Solidity assertion failed
[solidity::util::tag_comment*] = Solidity assertion failed
```

Expected behavior: a type error about duplicate operator bindings for `+` before any operator expression is type-checked.

Git commit: 9be66192f
solc 0.8.35-develop.2026.4.18+commit.9be66192.Linux.g++

Start at libsolidity/analysis/TypeChecker.cpp:1706 and reproduce the ICE with the provided mre.sol using solc --bin mre.sol. Trace duplicate using-for operator binding handling before the self-referential binary operation; done when the example reports a type error about duplicate + bindings instead of an internal compiler error.

Written by the indexing model from the issue text.