Guard web stub declarations with EL_SOUL_DEMO_BUILD to avoid soul-demo conflict

Dockerfile.stage

@@ -38,6 +38,7 @@ RUN cc -O2 -DHAVE_CURL -c el_runtime.c -I. -o el_runtime.o
 COPY dist/soul-demo.c dist/vessel_stubs.c ./
 
 RUN cc -O2 -rdynamic \
+       -DEL_SOUL_DEMO_BUILD \
        -o soul-demo \
        soul-demo.c vessel_stubs.c el_runtime.o \
        -lcurl -lpthread -ldl -lm -lssl -lcrypto

runtime/el_runtime.h

@@ -883,7 +883,13 @@ el_val_t  __args_json(void);
  * el_val_t return type instead of an implicit int.  Without these, the
  * ci-base elb (which does not emit extern-fn forward decls for stub-only
  * functions) produces truncated 32-bit returns on 64-bit Linux → segfault.
+ *
+ * Guarded by EL_SOUL_DEMO_BUILD: soul-demo.c includes this header but
+ * defines its own (different-arity) versions of some of these functions.
+ * Dockerfile.stage compiles soul-demo with -DEL_SOUL_DEMO_BUILD to skip
+ * this block and avoid conflicting-types errors.
  */
+#ifndef EL_SOUL_DEMO_BUILD
 el_val_t  http_get_auth(el_val_t url, el_val_t tok);
 el_val_t  http_post_auth(el_val_t url, el_val_t tok, el_val_t body);
 el_val_t  http_post_auth_json(el_val_t url, el_val_t tok, el_val_t body);
@@ -896,6 +902,7 @@ el_val_t  gcs_write(el_val_t bucket, el_val_t object_name, el_val_t content);
 el_val_t  gcs_read(el_val_t bucket, el_val_t object_name);
 el_val_t  cwd(void);
 el_val_t  color_bold(el_val_t s);
+#endif /* EL_SOUL_DEMO_BUILD */
 
 #ifdef __cplusplus
 }