fix(report-api): return 400 instead of 500 for invalid technology and date input

[max-ostapenko]

Summary

Two input bugs made report-api return 500 for bad client input. Between them they caused 7 of the 9 500 responses in the last 14 days of production logs.

/v1/technologies with more than 30 technologies (6 of the 500s)

validateTechnologyArray() returns null when the list is longer than Firestore's in limit of 30. queryTechnologies read technologies.length before checking for null, so it crashed with TypeError: Cannot read properties of null (reading 'length'), and the existing 400 error never ran. It now checks for null first, the same way queryVersions already does.

Example failing request: /v1/technologies?technology=WordPress,Joomla,Drupal,… (33 technologies).

/v1/cwv-distribution?date=undefined (1 of the 500s)

The string "undefined" was passed to BigQuery as @date, and the query failed with Cannot query over table 'httparchive.crawl.pages' without a filter over column(s) 'date' that can be used for partition elimination. The controller now accepts only YYYY-MM-DD or latest and returns a 400 validation error for anything else.

Whatever sends date=undefined (probably the Tech Report frontend building the URL before it has a date) should be fixed separately.

Tests

• Added a route test for each case. Both fail without the fix (500 and 200 instead of 400).
• report-api: 120/120 tests pass, lint clean.