Summary

Adds support for binary OTLP protobuf ingest on the existing OTLP/HTTP trace and log endpoints.

Why

Motel currently accepts OTLP protobuf-JSON payloads, but many OpenTelemetry SDKs send binary protobuf by default. In particular, Go’s standard OTLP/HTTP exporters, such as go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp, default to Content-Type: application/x-protobuf.
Without protobuf support, a default Go OpenTelemetry setup cannot send traces/logs to Motel without additional exporter configuration.

Changes

• Decode application/x-protobuf and application/protobuf requests for:
  • POST /v1/traces
  • POST /v1/logs
• Preserve existing application/json protobuf-JSON ingest behavior.
• Normalize decoded protobuf IDs and byte values into the protobuf-JSON shape expected by the existing telemetry store.
• Add focused unit coverage for protobuf trace and log decoding.
• Update README, copied setup instructions, OpenAPI descriptions, and motel-debug docs to mention protobuf support.

Scope note

The runtime change is intentionally small: the ingest handlers now choose JSON vs protobuf decoding based on Content-Type, then pass the resulting protobuf-JSON-shaped payload into the existing ingest path.
The remaining file changes are supporting updates:

• Tests cover protobuf decoding for traces and logs.
• Docs/setup text/OpenAPI descriptions were updated so users know both OTLP/HTTP encodings are supported.
• package.json/bun.lock add the direct OTLP transformer dependency used for decoding the generated OTLP protobuf messages.

Verification

• bun run typecheck
• bun run test