Track auction telemetry PR #813

[ChristianPavilonis]

Tracking

Track implementation and review follow-up for PR #813: Add server-side auction telemetry.

Scope

• Emit structured auction telemetry for completed auctions across /auction, /__ts/page-bids, and initial-navigation SSAT dispatch/collect.
• Preserve privacy guarantees for emitted fields, especially normalized/redacted page paths.
• Preserve provider failure, timeout, and mediator failure classifications in telemetry.
• Make the Fastly auction telemetry log endpoint configurable while retaining ts_auction_events as the default.
• Keep review-driven cleanup/refactoring tracked with the PR.

Validation

PR validation should include formatting, workspace tests, clippy, and Fastly adapter wasm check.