[tanfarming]

This adds one string metric, technical_operations.suspected_bot, to the MARS (ads_backend) interaction ping. It records why MARS's server-side detection flagged an ad interaction as suspected bot traffic (for example over_limit or stale), and is empty if the interaction wasn't flagged. It's Category 1 (Technical) and adds no new user data. We'll use it to exclude invalid traffic from impression and click reporting, and to tune detection.

Sample values for technical_operations.suspected_bot:

Value	Meaning
"" (empty)	Not flagged
over_limit	Too many impressions/clicks for the same ad request within a short window
stale	The ad was served longer ago than the detection policy's max age

It's a string rather than a boolean so it can carry the reason the detector returns. New reasons can be added in MARS without a schema change. Empty means not flagged.

• data review https://bugzilla.mozilla.org/show_bug.cgi?id=2082461