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.

server/packages/tavolo-app/README.md

@@ -12,9 +12,11 @@ The deployable tavolo application: the composition root wiring
   `tavolo.app:app` for granian.
 - `config.py` — environment-driven frozen `Settings`.
 - `telemetry.py` — the optional OpenTelemetry wiring beyond kaya-otel:
-  meter/logger providers, the `tavolo.active_users`/`tavolo.ongoing_games`
-  gauges (polled from the stores), process/CPython metrics via
-  `opentelemetry-instrumentation-system-metrics` and OTLP log export.
+  meter/tracer/logger providers, the
+  `tavolo.active_users`/`tavolo.ongoing_games` gauges (polled from the
+  stores), process/CPython metrics via
+  `opentelemetry-instrumentation-system-metrics`, Postgres/Redis query
+  spans via the asyncpg/redis instrumentations, and OTLP log export.
 - `aerich_config.py` — Tortoise ORM configuration consumed by the aerich
   CLI (migrations live in `server/migrations/`; aerich itself is
   configured via the `[tool.aerich]` section of `server/pyproject.toml`).