fix: normalize configured env values

[dp127001]

Summary

• normalize configured env entries before merging into the spawned child-process environment
• unwrap string values from Paperclip-style env objects such as { value: "..." } and { plain: "..." }
• ignore unresolved non-string objects instead of coercing them to [object Object]
• add regression tests covering both value-shape variants and overlay behavior

Problem

Paperclip can hand adapter env settings to the Hermes adapter as typed objects rather than raw strings. The adapter was doing a blind merge into process.env, which coerced those objects to [object Object]. That breaks runtime settings like HERMES_HOME, API URLs, and similar path/token values before Hermes even starts.

Test Plan

• npm test

Notes

This keeps the fix narrow and backward-compatible:

• raw strings still pass through unchanged
• supported wrapper object shapes are unwrapped
• unknown object shapes are ignored rather than stringified