Elixir adapter for AnvilClient - direct in-process integration.

This adapter makes direct function calls to the Anvil application when Ingot and Anvil are deployed together in the same Erlang VM.

When Anvil is fully integrated, this adapter will:

• Call Anvil.Queue or equivalent modules
• Translate Anvil domain structs to Ingot DTOs
• Handle errors and normalize them to standard client errors
• Apply timeouts and retries for resilience