Replace Ambiguous Tuples with Named Structs for Clarity and Type Safety

[NGA-TRAN]

The codebase currently overuses raw tuples (e.g., Result<(String, String)>), which negatively impacts readability and makes our intent opaque—both to developers and the compiler.

For example:

Result<(String, String)> // What do these values represent?

This introduces potential bugs from misordered usage and lacks semantic meaning.

Proposed Solution:

• Define meaningful types in vocab.rs, such as:

struct Host {
    name: String,
    addr: String,
}```

  - Refactor function signatures and return values to use named structs instead of raw tuples
  - Improve IDE/tooling support and code self-documentation in the process

This will make the codebase more intuitive, less error-prone, and easier to evolve over time.

[NGA-TRAN]

Many have done in #42 but there are more

[gabotechs]

Done in #68