Add quantiles for WAE metrics

[rtalvarez]

Pull Request Template

Description

Adds quantile breakdown of WAE metrics data

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)
• Documentation update
• Code refactoring
• Other (please describe):

Testing

Verified new query runs

DEBUG[2026-05-19 13:36:04] func:main.(*WAEClient).Query file:wae.go WAE query (account=acc):
                        SELECT
                                index1 AS metric_type,
                                blob1 AS label,
                                quantileWeighted(0.50, double1, _sample_interval) AS p50_ms,
                                quantileWeighted(0.75, double1, _sample_interval) AS p75_ms,
                                quantileWeighted(0.99, double1, _sample_interval) AS p99_ms,
                                quantileWeighted(0.999, double1, _sample_interval) AS p999_ms
                        FROM data
                        WHERE timestamp > NOW() - INTERVAL '5' MINUTE
                        GROUP BY index1, blob1
                        FORMAT JSON

Code Quality

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation

Before Submitting

Please ensure you have completed the following before submitting your PR:

# Run comprehensive tests
make pr-tests

If the above command fails, please fix the issues before submitting your PR.

Additional Notes

Add any other context about the pull request here.