fix(crypto): re-export ml_dsa_65 primitives

[aleksuss]

The PR adds re-export for types:

• MlDsa65PublicKey
• MlDsa65PublicKeyHandle,
• MlDsa65Signature,
  and the constant ML_DSA_65_PUBLIC_KEY_LENGTH.

[Copilot]

Pull request overview

Adds public re-exports from near_crypto for ML-DSA-65 primitives so downstream crates can use the concrete ML-DSA-65 key/signature types (and the pubkey length constant) without reaching into the private signature module. Also updates a test-only internal event-draining loop to use UnboundedReceiver::try_recv instead of try_next.

Changes:

• Re-export MlDsa65PublicKey, MlDsa65PublicKeyHandle, MlDsa65Signature, and ML_DSA_65_PUBLIC_KEY_LENGTH from core/crypto.
• Replace UnboundedReceiver::try_next with try_recv in ChunkExecutorActor’s testonly helper loop.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
core/crypto/src/lib.rs	Re-exports additional ML-DSA-65 types/constants from the signature module.
chain/client/src/spice/chunk_executor_actor.rs	Updates test-only internal event draining to use try_recv on unbounded receivers.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 72.61%. Comparing base (715e0f9) to head (cfc4bd3).
⚠️ Report is 3 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #15969   +/-   ##
=======================================
  Coverage   72.60%   72.61%           
=======================================
  Files         952      952           
  Lines      205109   205109           
  Branches   205109   205109           
=======================================
+ Hits       148914   148930   +16     
+ Misses      51218    51206   -12     
+ Partials     4977     4973    -4     

Flag	Coverage Δ
pytests-nightly	1.10% <ø> (ø)
unittests	69.55% <ø> (+<0.01%)	⬆️
unittests-nightly	69.53% <ø> (-0.01%)	⬇️
unittests-spice	66.99% <ø> (-0.01%)	⬇️

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