To set up a REPL that has cljs.core available, we need to re-partition the ESP32 and allocate more memory in Espruino for "JsVars".
The default Espruino bootloader.bin, pre-built variants of partitions_esprinuo.bin and rebuilt espruino_esp32.bin, and the ClojureScript runtime core.bin are also available here.
bootloader.bin gets flashed to 0x1000, partitions_espruino.bin gets flashed to 0x8000, and espruino_esp32.bin gets flashed to 0x10000 as per a usual ESP32 Espruino setup, and we put the ClojureScript runtime at 0x2C0000: