chore: Enable clang-tidy check for CRTP constructor accessibility

[godexsoft]

High Level Overview of Change

This PR enables bugprone-crtp-constructor-accessibility and fixes the few compilation issues we got from enabling it.

Context of Change

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Refactor (non-breaking change that only restructures code)
• Performance (increase or change in throughput and/or latency)
• Tests (you added tests for code that already exists, or your new feature included in this PR)
• Documentation update
• Chore (no impact to binary, e.g. .gitignore, formatting, dropping support for older tooling)
• Release

API Impact

• Public API: New feature (new methods and/or new fields)
• Public API: Breaking change (in general, breaking changes should only impact the next api_version)
• libxrpl change (any change that may affect libxrpl or dependents of libxrpl)
• Peer protocol change (must be backward compatible or bump the peer protocol version)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.8%. Comparing base (1a4c359) to head (fb00b3c).
⚠️ Report is 3 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff           @@
##           develop   #6452   +/-   ##
=======================================
  Coverage     79.8%   79.8%           
=======================================
  Files          878     878           
  Lines        67887   67895    +8     
  Branches      7554    7551    -3     
=======================================
+ Hits         54196   54212   +16     
+ Misses       13691   13683    -8     

Files with missing lines	Coverage Δ
src/libxrpl/basics/ResolverAsio.cpp	91.1% <ø> (ø)
src/xrpld/app/paths/detail/BookStep.cpp	95.5% <100.0%> (+<0.1%)	⬆️
src/xrpld/app/paths/detail/DirectStep.cpp	83.9% <100.0%> (+0.2%)	⬆️
src/xrpld/app/paths/detail/XRPEndpointStep.cpp	83.3% <100.0%> (+0.3%)	⬆️

... and 4 files with indirect coverage changes

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[Copilot]

Pull request overview

Enables the bugprone-crtp-constructor-accessibility clang-tidy check and updates several CRTP-style classes to satisfy the new rule by tightening base-constructor accessibility.

Changes:

• Enable bugprone-crtp-constructor-accessibility in .clang-tidy.
• Make CRTP base constructors non-public and add friend TDerived/friend Derived where needed.
• Replace inherited constructors (using Base::Base) with explicit derived constructors in affected step types.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/xrpld/app/paths/detail/XRPEndpointStep.cpp	Makes CRTP base ctor non-public and adds friendship; adds explicit ctor for XRPEndpointPaymentStep.
src/xrpld/app/paths/detail/DirectStep.cpp	Makes CRTP base ctor private + friends derived; replaces inherited ctors with explicit ctors in derived classes.
src/xrpld/app/paths/detail/BookStep.cpp	Makes CRTP base ctor private + friends derived; adds explicit ctor for BookPaymentStep.
src/test/app/XChain_test.cpp	Updates CRTP-like test helper to have a non-public base ctor and friends the derived type.
src/libxrpl/basics/ResolverAsio.cpp	Makes AsyncObject ctor non-public and friends Derived for CRTP compliance.
.clang-tidy	Enables the new bugprone check and reorders a few existing checks in the list.

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[a1q123456]

lgtm