Name request traces by route, and no colour codes off a terminal (#87, #88)

A request's trace was named by its path, so every item's GUID in
POST /api/entries/{feed_id}/{guid}/flags made a trace name of its own and
nothing grouped in Tempo. A route layer now renames it once routing has
matched. It renames the OpenTelemetry span directly: tracing-opentelemetry
drops a recorded otel.name once the span has been entered, and access_log
enters it before routing runs.

tracing-subscriber's fmt layer writes ANSI colour by default, so docker
logs and Loki (through Alloy) carried escape codes on every line, which
each query had to strip. Colour is now for a terminal only.

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

src/main.rs

@@ -191,6 +191,9 @@ async fn main() -> Result<()> {
             .with(
                 tracing_subscriber::fmt::layer()
                     .with_writer(std::io::stderr)
+                    // Colour for a terminal only: in docker logs and Loki the escapes are noise
+                    // every query has to strip (#88).
+                    .with_ansi(std::io::IsTerminal::is_terminal(&std::io::stderr()))
                     .with_filter(stderr_filter),
             )
             .with(logbuf::RingLayer.with_filter(ui_filter))