fix(net): preserve ECIESError in connect_without_timeout

[phrwlk]

Previously, ECIESStream::connect_without_timeout() remapped any error from ECIESCodec::new_client() to io::Error::other("invalid handshake"), which collapsed structured ECIESError variants (e.g., Secp256k1) into a generic IO error.

This broke downstream error classification in the networking layer, which matches on ECIESErrorImpl variants to decide on backoff and whether a failure is fatal.

Changes:

• Propagate the original ECIESError from ECIESCodec::new_client() to preserve semantics.
• Add a regression test that passes an invalid remote_id and asserts the error’s inner
  variant is ECIESErrorImpl::Secp256k1(_), not IO.

This aligns client error handling with server-side incoming() and ensures consistent, actionable error semantics for callers.

[mattsse]

this is better

[codspeed-hq]

CodSpeed Performance Report

Merging #19558 will improve performances by 10.87%

_{Comparing phrwlk:fix/ecies-propagate-handshake-error (fe6d1ea) with main (7997cd4)}

Summary

⚡ 1 improvement
✅ 76 untouched

Benchmarks breakdown

	Benchmark	BASE	HEAD	Change
⚡	hash builder[init size 10000 | update size 100 | num updates 5]	45.3 ms	40.9 ms	+10.87%