Every page heading printed the modules JSON array as is
(["LilyGo_SSD1306","WebUI","LORA"]). Show it as a comma separated list.
The heading buffer was also filled with serializeJson(modules, jsonChar,
measureJson(modules) + 1), i.e. the size of the text rather than of the
100 bytes buffer, which overflows when many modules are enabled; the new
helper (and the boot log) use the buffer size.
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
server.arg() returns a String by value, so the pointer from c_str()
pointed into a temporary that was destroyed before strlen()/strcpy().
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
