point Makefile at foundation/el rather than /usr/local/lib/el

elc is not installed system-wide; resolve ELC and EL_LIB from
the monorepo at $(HOME)/Development/neuron-technologies/foundation/el
so plain `make build` works without extra env vars.

Makefile

@@ -1,7 +1,8 @@
-EL_LIB ?= /usr/local/lib/el
-ELC    ?= elc
-CC     ?= cc
-CFLAGS := -std=c11 -O2 -I$(EL_LIB)
+EL_ROOT ?= $(HOME)/Development/neuron-technologies/foundation/el
+EL_LIB  ?= $(EL_ROOT)/el-compiler/runtime
+ELC     ?= $(EL_ROOT)/dist/platform/elc
+CC      ?= cc
+CFLAGS  := -std=c11 -O2 -I$(EL_LIB)
 
 .PHONY: build clean install