fix(query): improve selectivity estimation for boolean expressions

[forsaken628]

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Summary

• estimate non-nullable Boolean predicates without column statistics using an even true/false distribution
• handle Boolean comparisons according to their possible outcomes, while keeping nullable Boolean comparisons unknown when null statistics are unavailable
• preserve concrete numeric estimates in mixed AND predicates instead of letting Unknown or LowerBound fallbacks override them

Tests

• Unit Test
• Logic Test
• Benchmark Test
• No Test - Explain why

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 could cause existing functionality not to work as expected)
• Documentation Update
• Refactoring
• Performance Improvement
• Other (please describe):

AI assistance

• AI usage: An AI coding agent assisted with implementation.
• Responsible human: @forsaken628
• The responsible human has read every line of this diff and can explain each change

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This change is 

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🤖 CI Job Analysis (Retry 1)

Workflow: 30643497863

📊 Summary

• Total Jobs: 90
• Failed Jobs: 2
• Retryable: 0
• Code Issues: 2

❌ NO RETRY NEEDED

All failures appear to be code/test issues requiring manual fixes.

🔍 Job Details

• ❌ linux / sqllogic / standalone (standalone, 2c, http): Not retryable (Code/Test)
• ❌ linux / sqllogic / standalone (standalone, 2c, hybrid): Not retryable (Code/Test)

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Automated analysis using job annotations to distinguish infrastructure issues (auto-retried) from code/test issues (manual fixes needed).