b83a999b14 btcsignals: delete broken scoped_connection move assignment (Thomas)
Pull request description:
The defaulted move-assignment operator for `scoped_connection` overwrites `m_conn` without first calling `disconnect()`. Since disconnection is signaled via the liveness flag (which is never cleared) the old callback remains registered in the signal and keeps firing, violating the RAII contract:
```cpp
int val{0};
btcsignals::scoped_connection sc0 = sig.connect(IncrementCallback);
btcsignals::scoped_connection sc1 = sig.connect(SquareCallback);
sc0 = std::move(sc1);
val = 3; sig(val);
// Expected: 9 (only SquareCallback)
// Actual: 16 (both callbacks fire, old connection leaked)
```
Move assignment is unused in the codebase, so following the review discussion this deletes the broken operator instead of fixing it. A correct implementation can be added if a use case arises.
Earlier versions of this PR fixed the operator and added a default constructor to enable the member-variable assignment pattern; that was dropped in favor of removing the unused operation.
ACKs for top commit:
maflcko:
lgtm ACK b83a999b14
sedited:
ACK b83a999b14
Tree-SHA512: 794347e9cb868d50957ea298f7df6eac5b9f55b9d35ab09e41be269923c45e0709194431dea66b7977c74f802150ba53cb2d12d35937f4966ec302bffb9c95f8
3b712b9d02