Add sync auditlogreceiver with WAL durability and circuit breaker.

[MJarmo]

Assisted-by: Composer

Description

Adds the auditlogreceiver component: an HTTP OTLP receiver for signed audit
logs on the dedicated /v1/audit endpoint (default listen 0.0.0.0:4310).

The receiver is sync-only (response_mode: sync). Each request is written to a
required storage-backed WAL before pipeline delivery and cleared after success,
so ingest can survive transient backend failures.

HTTP outcomes:

• 200 — delivered through the pipeline
• 400 — permanent failure (e.g. integrity rejected)
• 503 — transient failure (open_behavior: reject)
• 202 — accepted into WAL while the circuit is open (open_behavior: accept),
  then replayed by the recovery ticker

Downstream sinks must treat audit.record.id as an idempotency key
(at-least-once delivery).

Link to tracking issue

Fixes

Testing

• Unit/integration coverage under receiver/auditlogreceiver
• Local otelauditcol compose smoke: SDK export to https://localhost:4310/v1/audit
  (or HTTP equivalent) and WAL store/clear log lines on success

Documentation

• receiver/auditlogreceiver/README.md — endpoint, sync semantics, circuit
  breaker, config defaults
• receiver/auditlogreceiver/example-config.yaml — reference sync config

Authorship

• I, a human, wrote this pull request description myself.