Fix Unicode env parsing in infra_secrets for stage startup.

Use unicode:characters_to_binary for os:getenv values so Cyrillic placeholder passwords fail with weak_secret instead of badarg crash.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/infra/infra_secrets.erl

@@ -51,7 +51,7 @@ require_admin_seed_email(EnvKey) ->
   case os:getenv(EnvKey) of
     false -> {error, {missing_secret, list_to_atom(EnvKey)}};
     "" -> {error, {missing_secret, list_to_atom(EnvKey)}};
-    Email -> {ok, list_to_binary(Email)}
+    Email -> {ok, env_to_binary(Email)}
   end.
 
 -spec require_admin_seed_password(string()) ->
@@ -61,7 +61,7 @@ require_admin_seed_password(EnvKey) ->
     false -> {error, {missing_secret, list_to_atom(EnvKey)}};
     "" -> {error, {missing_secret, list_to_atom(EnvKey)}};
     Pass ->
-      Bin = list_to_binary(Pass),
+      Bin = env_to_binary(Pass),
       case is_strong_secret(Bin) of
         true -> {ok, Bin};
         false -> {error, {weak_secret, list_to_atom(EnvKey)}}
@@ -124,9 +124,13 @@ os_getenv_binary(Key) ->
   case os:getenv(Key) of
     false -> undefined;
     "" -> undefined;
-    Val -> list_to_binary(Val)
+    Val -> env_to_binary(Val)
   end.
 
+%% os:getenv/1 returns Unicode charlists; list_to_binary/1 only accepts byte iolists.
+env_to_binary(Val) when is_binary(Val) -> Val;
+env_to_binary(Val) when is_list(Val) -> unicode:characters_to_binary(Val).
+
 dev_warn_if_weak(_Name, undefined) -> ok;
 dev_warn_if_weak(Name, Secret) ->
   case is_strong_secret(Secret) of