feat: add comprehensive Parquet export validation script (PE-8458)

[djwhitt]

Summary

Implements a comprehensive validation script to compare Parquet exports from different methods (TypeScript vs bash) and validate against source SQLite databases.

Changes

• Add scripts/validate-parquet with three validation modes:
  • source: Validate Parquet against SQLite databases
  • compare: Compare two Parquet export directories
  • full: Both source and cross-export validation (default)

Features

• Row count verification between SQLite source and Parquet exports
• Data sampling with configurable sample rates (default 1%)
• File structure comparison between different export methods
• Schema validation ensuring column types match
• Height range consistency checking
• Color-coded console output with ✓/✗/⚠ indicators
• Detailed log files and JSON summary reports
• Smart defaults for common directory structures
• Exit codes for programmatic usage

Usage Examples

# Full validation with defaults
./scripts/validate-parquet

# Quick metadata-only check
./scripts/validate-parquet --quick

# Validate specific height range
./scripts/validate-parquet --start-height 900000 --end-height 910000

# Compare export methods only
./scripts/validate-parquet --mode compare

Test plan

• Test with existing Parquet exports from both TypeScript and bash methods
• Verify row count accuracy against SQLite databases
• Test height range filtering functionality
• Validate JSON report generation
• Test error handling with missing files/directories

Related

• JIRA: PE-8458
• Addresses data integrity validation between export methods

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