Trace Postgres and Redis queries with the contrib instrumentations

Builds the TracerProvider in tavolo.telemetry (kaya-otel's is private) and
injects it into kaya-otel, then instruments asyncpg and redis through
opentelemetry-instrumentation-asyncpg/redis. Redis command values are
redacted and asyncpg spans carry the parameterized SQL only.

docker-compose.yml

@@ -122,8 +122,9 @@ services:
       CORS_ALLOW_CREDENTIALS: ${CORS_ALLOW_CREDENTIALS:-}
       CORS_EXPOSE_HEADERS: ${CORS_EXPOSE_HEADERS:-}
       CORS_MAX_AGE: ${CORS_MAX_AGE:-}
-      # OpenTelemetry (kaya-otel + system-metrics): traces, metrics and
-      # logs via OTLP/HTTP, disabled unless OTEL_ENABLED is set.
+      # OpenTelemetry (kaya-otel + contrib instrumentations): traces
+      # (HTTP/WebSocket, Postgres, Redis), metrics and logs via OTLP/HTTP,
+      # disabled unless OTEL_ENABLED is set.
       # The image bundles the otel extra (see packages/tavolo-app/pyproject.toml
       # and server/requirements.txt).
       OTEL_ENABLED: ${OTEL_ENABLED:-}