[codex] Fix pod plugin alias expansion and add regression test

[mikehostetler]

Summary

• expand user-provided :plugins in Jido.Pod.__using__/1 via Definition.expand_and_eval_literal_option/2 before Macro.escape/1
• merge pod plugins with expanded user plugins (pod_plugins ++ (user_plugins || []))
• add a regression test that compiles a pod using an aliased plugin module in plugins: and verifies the module is resolved and mounted

Root Cause

Jido.Pod.__using__/1 passed opts[:plugins] through raw. When the pod options were later escaped, aliased plugin modules remained as alias AST tuples rather than resolved module atoms, causing plugin normalization/compile checks to fail.

Impact

Pods can now safely use aliased plugin modules in plugins: declarations. This restores expected macro behavior and prevents compile-time plugin extraction failures.

Validation

• mix test test/jido/pod_test.exs test/jido/pod/topology_test.exs test/jido/pod/mutation/planner_test.exs test/jido/pod/mutation_runtime_test.exs test/jido/pod/runtime_test.exs test/jido/pod/telemetry_test.exs

[mikehostetler]

Meant to attach this to #239 - closing