TRAC-469: add support for wae metrics

[rtalvarez]

Pull Request Template

Description

Adds support for fetching Analytics Engine metrics via the SQL API, and adds a converter into prometheus metrics, reading from WAE_DATASET_SCRIPT_NAME_ENV datastore.

Generic implementation exposes label, metric_type and script_name, assuming the worker knows the shape of their 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 the exporter is able to execute the API call

DEBUG[2026-05-18 10:04:29] func:main.(*WAEClient).Query file:wae.go WAE query (account=XYZ):
                        SELECT
                                index1 AS metric_type,
                                blob1 AS label,
                                SUM(_sample_interval * double1) / SUM(_sample_interval) AS avg_duration_ms,
                                SUM(_sample_interval) AS total_requests
                        FROM script_name
                        WHERE timestamp > NOW() - INTERVAL '5' MINUTE
                        GROUP BY index1, blob1
                        FORMAT JSON

I have also verified that these show up in localhost:8080/metrics with the right format

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.

[chanceaclark]

🍹 I would also say that it may be inaccurate as well. We've seen where KV reports "bad" metrics, as in high latency, due to a high-ish aggregation window.

[rtalvarez]

yeah, honestly we'll see how it goes. we can always make this value configurable in case we need to tweak it w/o code change