Improve Error Reporting and Messaging for API Proxy Clients

[NGA-TRAN]

We’re working toward more consistent and useful error reporting in the codebase—particularly for clients interacting with the API proxy.

Current status:

• Some foundational work exists in result.rs
• We're leveraging thiserror and anyhow to reduce boilerplate and standardize error handling

Next steps:

• Ensure all errors exposed to API clients are informative, actionable, and consistent
• Expand usage of typed errors where appropriate
• Improve mapping between internal errors and client-facing messages
• Identify and close any gaps in error propagation and logging

Improving this will go a long way toward enhancing developer experience and debugging.

[gabotechs]

Done in #69