[Target] Encode invariants as a table of rules

[alexreinking]

Replaces the validators with a declarative framework for target invariants.

This also somewhat improves on the efficiency of the transactional setting invariant established in #9250

Checklist

• Tests added or updated (not required for docs, CI config, or typo fixes)
• Documentation updated (if public API changed)
• Python bindings updated (if public API changed)
• Benchmarks are included here if the change is intended to affect performance.
• Commits include AI attribution where applicable (see Code of Conduct)

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[codecov]

Codecov Report

❌ Patch coverage is 78.44828% with 50 lines in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (alexreinking/target-integrity@9886da2). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
src/Target.cpp	78.44%	39 Missing and 11 partials ⚠️

Additional details and impacted files

@@                       Coverage Diff                        @@
##             alexreinking/target-integrity    #9251   +/-   ##
================================================================
  Coverage                                 ?   70.25%           
================================================================
  Files                                    ?      255           
  Lines                                    ?    79024           
  Branches                                 ?    18907           
================================================================
  Hits                                     ?    55517           
  Misses                                   ?    17881           
  Partials                                 ?     5626           

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