feat(infra): add local-dev Docker Compose stack

Bring up Postgres + Redis + OTel Collector in one command so
contributors can run the BFF end-to-end without each setting up
the runtime services manually. Replaces the throwaway
`docker run postgres:17-alpine` one-liner that was in §3 of
docs/development.md.

What lands:

- `infra/local/dev.compose.yml` — three core services
  (postgres 17.2-alpine, redis 7.4-alpine,
  otel/opentelemetry-collector-contrib 0.115.0) plus two
  viewers gated behind Compose profiles (pgweb under
  `--profile dbtools`, Jaeger 1.62 under
  `--profile observability`). All ports overridable via .env;
  state in named volumes; healthchecks on the data services.
- `infra/local/.env.example` — credentials + ports template.
  POSTGRES_PASSWORD and REDIS_PASSWORD are mandatory (compose
  refuses to boot without them); other keys default sensibly.
- `infra/local/init/postgres/01-init.sql` — bootstrap SQL per
  ADR-0013: `audit_owner` / `audit_writer` / `audit_reader` /
  `audit_archiver` roles plus `audit` schema, with default
  privileges encoding the append-only contract (INSERT to
  writer, SELECT to reader, DELETE to archiver, no UPDATE /
  TRUNCATE to anyone). Applied on first Postgres boot only;
  documented re-run procedure in infra/README.md.
- `infra/local/otel-collector.yaml` — pipeline: OTLP gRPC/HTTP
  → batch → debug exporter (always) + forward to `jaeger:4317`
  (no-op when the observability profile is off; logs warn-level
  retry but doesn't block other exporters).

Surrounding docs updated:

- `infra/README.md` — new "Local-dev stack" section with
  service inventory, port table, first-time setup, operational
  tips. The `local/` row replaces the previous placeholder.
- `docs/development.md` §3 — rewritten to walk through the
  compose-based setup; cross-links to `infra/README.md` for
  the full reference. Roadmap entry for "Local infra recipe"
  removed from §8 (now implemented); "Observability dev-loop"
  entry adjusted to point at the new Jaeger profile.

Production parity is intentionally left for the on-prem
infrastructure ADR (phase 3b) — this is the dev-only stack.

infra/local/otel-collector.yaml

@@ -0,0 +1,65 @@
+# OpenTelemetry Collector config for the local-dev stack.
+#
+# v1 scope (per ADR-0012):
+#   - Accept OTLP from the BFF and the SPA on gRPC (4317) and HTTP
+#     (4318). The default OTEL_EXPORTER_OTLP_ENDPOINT in dev points
+#     here.
+#   - Batch + log everything to stdout via the `debug` exporter — the
+#     dev sees what their app emits without standing up a backend.
+#   - When the `observability` Compose profile is active, additionally
+#     forward to Jaeger (`jaeger:4317` on the internal Compose
+#     network). When the profile is inactive, the OTLP→Jaeger export
+#     fails at warn level but does not impact the debug pipeline.
+#
+# Production replaces the debug exporter with the proper backend
+# (chosen in the future on-prem infrastructure ADR — likely Tempo +
+# Loki + Mimir, or an OpenTelemetry-friendly all-in-one).
+
+receivers:
+  otlp:
+    protocols:
+      grpc:
+        endpoint: 0.0.0.0:4317
+      http:
+        endpoint: 0.0.0.0:4318
+
+processors:
+  batch:
+    # Small batches in dev so the developer sees output quickly.
+    timeout: 5s
+    send_batch_size: 100
+
+exporters:
+  debug:
+    verbosity: detailed
+  otlp/jaeger:
+    endpoint: jaeger:4317
+    tls:
+      insecure: true
+    sending_queue:
+      enabled: true
+      # When jaeger isn't running (profile off), retries fall back
+      # to a small queue rather than blocking the pipeline.
+      queue_size: 100
+    retry_on_failure:
+      enabled: true
+      initial_interval: 5s
+      max_interval: 30s
+
+service:
+  pipelines:
+    traces:
+      receivers: [otlp]
+      processors: [batch]
+      exporters: [debug, otlp/jaeger]
+    logs:
+      receivers: [otlp]
+      processors: [batch]
+      exporters: [debug]
+    metrics:
+      receivers: [otlp]
+      processors: [batch]
+      exporters: [debug]
+  telemetry:
+    logs:
+      level: info