Unbounded strcpy(response, ...) in POST()/GET() HTTP client helpers

[davidchatting-bot]

Where

Two sites in `src/YoYoWiFiManager.cpp`, both flagged in source with `//#TODO: test length?`:

`POST(const char *server, const char *path, const char *payload, char *contentType, char *response)`:
```cpp
if(response && httpResponseCode > 0) {
//#TODO: test length?
strcpy(response, http.getString().c_str());
}
```

`GET(const char *server, const char *path, char *response)`:
```cpp
if (httpResponseCode > 0) {
//#TODO: test length?
strcpy(response, http.getString().c_str());
}
```

Problem

Both copy an HTTP response body of arbitrary length (from whatever peer/server was called) into a caller-supplied fixed-size `char *response` buffer with no length check - the same overflow shape as the `setCredentials()`/`onYoYoRequestPOST()` bugs fixed in #56/#57, just on the outgoing request path (a device calling another peer) rather than the incoming request path. Any caller passing a fixed-size stack/heap buffer as `response` is exposed to a heap/stack overflow if the remote peer's response is longer than expected.

Suggested fix

Either:

• Take a `size_t responseSize` parameter at both call sites and bound the copy (`strncpy`/length check before copy, per the pattern used in the Heap buffer overflow: unbounded strcpy of untrusted JSON in setCredentials() #56 fix), or
• Change the signature to take a `String&` instead of `char *`, avoiding the fixed-buffer assumption entirely (there's already a `GET(..., JsonDocument&)` overload that avoids this problem the same way).