ipx-directory traces, and ipx's trace follows its calls there (#213)

The exporter setup and the traceparent parser move from ipx into ipx_directory::otel, which ipx
already depends on, so both binaries share them. The directory makes a span a request, a child of
the caller's traceparent, and a trace a refresher round with a span a feed; ipx sends the current
span's traceparent on every call to the directory and wraps each share in a span. The dashboard's
Traces row and the prod-check skill cover all three services.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/directory/Cargo.toml

@@ -12,6 +12,9 @@ anyhow.workspace = true
 axum.workspace = true
 clap.workspace = true
 ipx-feed.workspace = true
+opentelemetry.workspace = true
+opentelemetry-otlp.workspace = true
+opentelemetry_sdk.workspace = true
 reqwest.workspace = true
 sea-orm.workspace = true
 serde.workspace = true
@@ -20,6 +23,7 @@ sha2.workspace = true
 tokio.workspace = true
 toml.workspace = true
 tracing.workspace = true
+tracing-opentelemetry.workspace = true
 tracing-subscriber.workspace = true
 url.workspace = true