feat(side-dag): update APIs

[glevco]

Motivation

Update API response models to include side-dag and Proof-of-Authority related data.

Acceptance Criteria

• Add NATIVE_TOKEN_NAME and NATIVE_TOKEN_SYMBOL to HathorSettings and to the /v1a/version API.
• Add DECIMAL_PLACES and genesis hashes to the /v1a/version API.
• Update PoaBlock.to_json() to include PoA fields.
• Implement poa.get_signer_index_and_public_key() and update PoaBlockVerifier to use it.
• Add missing PoaBlock timestamp verification.
• Change pre-argument parsers to use create_parser(), adding support for environment variables.

Checklist

• If you are requesting a merge into master, confirm this code is production-ready and can be included in future releases as soon as it gets merged

[codecov]

Codecov Report

Attention: Patch coverage is 84.00000% with 8 lines in your changes missing coverage. Please review.

Project coverage is 85.07%. Comparing base (b3f3d3e) to head (fc3a749).

Files	Patch %	Lines
hathor/transaction/poa/poa_block.py	46.66%	8 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1071      +/-   ##
==========================================
- Coverage   85.08%   85.07%   -0.01%     
==========================================
  Files         309      309              
  Lines       23396    23421      +25     
  Branches     3529     3534       +5     
==========================================
+ Hits        19906    19926      +20     
- Misses       2790     2797       +7     
+ Partials      700      698       -2     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

The base branch was changed.