Add nowarn_missing_spec to test profile to fix test compilation

The test suites use -compile(export_all) and don't have -spec
annotations, which causes compilation to fail because the global
erl_opts includes both warn_missing_spec and warnings_as_errors.

https://claude.ai/code/session_01RBbLduNgvjWctN2Dj12UDY

Author: claude

rebar.config

@@ -39,7 +39,7 @@
 
 {profiles, [
     {test, [
-        {erl_opts, [nowarn_export_all]},
+        {erl_opts, [nowarn_export_all, nowarn_missing_spec]},
         {deps, [
             {meck, "~> 0.9"}
         ]}