Elixir adapter for ForgeClient - direct in-process integration.

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

When Forge is fully integrated, this adapter will:

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