feat: add modular Forth interpreter implementation

Co-authored-by: aider (openrouter/tencent/hy3-preview:free) <aider@aider.chat>

Makefile

@@ -0,0 +1,19 @@
+CC = gcc
+CFLAGS = -Wall -Wextra -g
+LDFLAGS =
+SRCS = forth_core.c forth_dict.c forth_words.c forth_interp.c main.c
+OBJS = $(SRCS:.c=.o)
+TARGET = forth
+
+all: $(TARGET)
+
+$(TARGET): $(OBJS)
+	$(CC) $(CFLAGS) -o $@ $^ $(LDFLAGS)
+
+%.o: %.c forth.h
+	$(CC) $(CFLAGS) -c $< -o $@
+
+clean:
+	rm -f $(OBJS) $(TARGET)
+
+.PHONY: all clean