Cut Trusted Server over to EdgeZero PR 275 #1507

Description

Move all six EdgeZero crates to EdgeZero PR 275 in one change, following the spec in #1506. Every outbound request goes through EdgeZero's HttpClient, Fastly runs on EdgeZero's canonical lifecycle (send_request_with_registries_and_hooks), and EdgeZero follows redirects. Trusted Server's outbound layer (PlatformHttpClient, PlatformBackend, backend naming, the four adapter clients), its redirect loop, and its Fastly response delivery are deleted, with no compatibility layer.

main pins EdgeZero v0.0.11 today. Repinning to PR 275 head 8f82547b without code changes leaves 167 compile errors. Three runtime breaks also compile cleanly: inbound bodies arrive as streams, three of the four adapter clients reject streamed request bodies, and EdgeZero's response framing rejects Trailer.

The spec's commit sequence has 11 steps. Development pins 8f82547b. The merge pins the qualified candidate from #1508.

Done when

• main pins the frozen PR 275 candidate that EdgeZero's qualification record names.
• The spec's dependents inventory command prints nothing.
• Every CI gate in AGENTS.md passes, along with the spec's new tests.
• The Fastly response diff against the previous build shows only the Fastly differences the spec lists.
• Issue Support multi-provider auction fan-out on the Cloudflare and Spin adapters #1484 (multi-provider fan-out on Cloudflare and Spin) is closed.

Affected area

Core (Edge Cookies, GDPR), Integrations, Fastly runtime, CI / Tooling, Documentation

Related

• Spec: Write the EdgeZero PR 275 cutover spec #1513 (pull request Cut Trusted Server over to EdgeZero PR 275 #1506)
• Epic: Integrate Auctioneer into Trusted Server on EdgeZero PR 275 #1505
• Merge waits on: Run Trusted Server's share of the EdgeZero PR 275 qualification #1508
• EdgeZero: feat: implement portable outbound HTTP and request lifecycle contracts edgezero#275