apps/api — OTLP ingestion endpoint, token auth, fast 202

[AKogut]

Context

Write-path throughput is bottleneck #1. Never block CI: validate, enqueue, ACK 202 immediately.

Scope

• Fastify server with OTLP/HTTP receiver (protobuf + JSON)
• Project-token auth (hashed tokens, per-project scoping)
• Payload validation against contracts; reject malformed with actionable errors
• Enqueue to durable queue; respond 202 with a receipt id
• Rate limiting + payload size caps + zstd handling
• Structured logging + self-instrumentation (dogfood OTel)

Acceptance criteria

• p99 ingestion latency independent of downstream processing
• Malformed/oversized payloads rejected without data loss on valid ones