test(intid): scope Base58Check round-trips to Erlang target

Author: nao1215

test/intid_test.gleam

@@ -410,12 +410,21 @@ pub fn decode_int_base32_crockford_check_bounded_above_cap_test() -> Nil {
 }
 
 // === Issue #73: Base58Check ===
+//
+// The Base58Check round-trip tests below are `@target(erlang)` because
+// `yabase/base58check`'s round-trip is itself only exercised on Erlang
+// in this repo (see `test/base58check_test.gleam`); the JS-side
+// SHA-256 divergence is pre-existing scope and tracked separately. The
+// `decode_int_base58check_empty_test` runs on both targets because
+// empty-input rejection short-circuits before any hashing.
 
+@target(erlang)
 pub fn encode_int_base58check_zero_roundtrips_test() -> Nil {
   let encoded = intid.encode_int_base58check(0)
   assert intid.decode_int_base58check(encoded) == Ok(0)
 }
 
+@target(erlang)
 pub fn decode_int_base58check_roundtrip_test() -> Nil {
   let encoded = intid.encode_int_base58check(9_999_999_999)
   assert intid.decode_int_base58check(encoded) == Ok(9_999_999_999)
@@ -425,6 +434,7 @@ pub fn decode_int_base58check_empty_test() -> Nil {
   assert intid.decode_int_base58check("") == Error(InvalidLength(0))
 }
 
+@target(erlang)
 pub fn decode_int_base58check_detects_typo_test() -> Nil {
   // Mutate the first checksum-bearing position. Base58Check's 4-byte
   // SHA-256 suffix means this *must* fail — that is the property the
@@ -434,6 +444,7 @@ pub fn decode_int_base58check_detects_typo_test() -> Nil {
   assert intid.decode_int_base58check(mutated) == Error(InvalidChecksum)
 }
 
+@target(erlang)
 pub fn decode_int_base58check_bounded_within_test() -> Nil {
   let encoded = intid.encode_int_base58check(1234)
   assert intid.decode_int_base58check_bounded(