chore: AI code quality improvements (run 29225865300)

[github-actions]

Summary

Automated PR from the AI Code Quality Agent (run 29225865300).

Changes may include (per CONVENTIONS.MD)

• Auto-formatting via Spotless (Java) and Prettier (JS/TS)
• Javadoc added to public classes / interfaces that had none
• Immutability first: List.of() / Set.of() replaced with Guava ImmutableList.of() / ImmutableSet.of(); Collectors.toSet() replaced with ImmutableSet.toImmutableSet()
• Ordered mutability: HashMap → LinkedHashMap, HashSet → LinkedHashSet; Collectors.toMap → PepperStreamHelperHacked.toLinkedMap; Collectors.groupingBy with LinkedHashMap::new
• Logging: SLF4J {} placeholders instead of string concatenation
• Method ordering: recently-touched files reordered to follow the Stepdown Rule (entry points first, callees below their first caller)

Review checklist

• CI passes (Build, Spotless, Static Analysis)
• No unintended logic changes
• Javadoc is accurate and meaningful
• Review .github/ai-quality-discoveries.md — promote confirmed new patterns to CLAUDE.md, discard false positives

[codecov]

Codecov Report

❌ Patch coverage is 66.66667% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 78.58%. Comparing base (228818f) to head (054cd89).

Files with missing lines	Patch %	Lines
...hoc/map/factory/BenchmarkColumnarSliceFactory.java	0.00%	2 Missing ⚠️
...able/sql/join/KnownColumnsExpressionExtractor.java	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #898      +/-   ##
============================================
+ Coverage     78.56%   78.58%   +0.01%     
  Complexity      109      109              
============================================
  Files           751      751              
  Lines         23174    23174              
  Branches       2670     2670              
============================================
+ Hits          18207    18211       +4     
+ Misses         3972     3969       -3     
+ Partials        995      994       -1     

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
75.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud