Portable DynamoDB and celld providers over EdgeZero's outbound HTTP, verified on Fastly #474

Summary

Portable DynamoDB and celld providers over EdgeZero's outbound HTTP, verified on Fastly, with the WASM credential source and a conditional-write latency budget stated.

Behavior

The same providers run on every adapter over EdgeZero's outbound HTTP, while the native stores (Fastly KV, Cloudflare KV, Spin KV) stay on their own platform (DEC-3). Each states the credential source it uses on WASM targets and a latency budget for a conditional write.

Acceptance criteria

• The contract suite passes against both on Fastly
• EZI-2c and EZI-2s run it on Cloudflare and Spin

Dependencies

Blocked by:

• DynamoDB and celld providers on Axum meet the record contract #473 DynamoDB and celld providers on Axum meet the record contract (new in this plan)
• PR feat: implement portable outbound HTTP and request lifecycle contracts #275 feat: implement portable outbound HTTP and request lifecycle contracts

Blocks:

• EZI-2c Cloudflare record store: portable providers and Workers KV pass the record contract (new in this plan)
• EZI-2s Spin record store: portable providers and Spin KV pass the record contract (new in this plan)

Related

• Needed by Server-side identity on every adapter trusted-server#1558, server-side identity on every adapter. Planned in wave 10 (after the MVP: Cloudflare); priority P2, size XL.
• Requirement EZI-2p in the design.