feat: project foundation — monorepo setup, shared config, redis streams, telemetry

- pyproject.toml with core deps and optional dep groups per service
- shared/config.py: Pydantic BaseSettings with TRADING_ env prefix
- shared/redis_streams.py: StreamPublisher/StreamConsumer wrappers
- shared/telemetry.py: OpenTelemetry + Prometheus metric export
- tests for Redis Streams helpers (5 passing)

shared/telemetry.py

@@ -0,0 +1,21 @@
+"""OpenTelemetry setup with Prometheus metric export."""
+
+from opentelemetry import metrics
+from opentelemetry.exporter.prometheus import PrometheusMetricReader
+from opentelemetry.sdk.metrics import MeterProvider
+from prometheus_client import start_http_server
+
+
+def setup_telemetry(service_name: str, metrics_port: int = 9090) -> metrics.Meter:
+    """Initialise an OpenTelemetry MeterProvider backed by Prometheus.
+
+    A Prometheus-compatible HTTP server is started on *metrics_port*
+    so that an external Prometheus instance can scrape ``/metrics``.
+
+    Returns a ``Meter`` that services use to create counters, histograms, etc.
+    """
+    reader = PrometheusMetricReader()
+    provider = MeterProvider(metric_readers=[reader])
+    metrics.set_meter_provider(provider)
+    start_http_server(metrics_port)
+    return metrics.get_meter(service_name)