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/web.rs

@@ -4,7 +4,7 @@ use anyhow::{Context, Result};
 use axum::http::HeaderMap;
 use axum::{
     Json, Router,
-    extract::{Path, Query, Request, State},
+    extract::{MatchedPath, Path, Query, Request, State},
     http::{StatusCode, header},
     middleware::{self, Next},
     response::{
@@ -79,6 +79,7 @@ pub fn router(state: WebState) -> Router {
         .route("/app.css", get(app_css))
         .route("/login.js", get(login_js))
         .route("/inter.woff2", get(inter))
+        .route_layer(middleware::from_fn(name_span))
         .layer(middleware::from_fn(access_log))
         .with_state(state)
 }
@@ -1930,6 +1931,19 @@ async fn logs(user: crate::db::User, Query(q): Query<LogQuery>) -> Result<Json<L
     Ok(Json(LogPage { lines, latest }))
 }
 
+/// Names a request's trace by its route, `POST /api/entries/{feed_id}/{guid}/flags`, once routing
+/// has found it. Named by the path `access_log` sees, every item's GUID was a trace name of its
+/// own, and nothing grouped. A route layer, because only one runs after routing. Renamed on the
+/// OpenTelemetry span itself: recording `otel.name` is ignored once the span has started.
+async fn name_span(route: MatchedPath, req: Request, next: Next) -> Response {
+    use opentelemetry::trace::TraceContextExt;
+    use tracing_opentelemetry::OpenTelemetrySpanExt;
+    let span = tracing::Span::current();
+    span.context().span().update_name(format!("{} {}", req.method(), route.as_str()));
+    span.record("http.route", route.as_str());
+    next.run(req).await
+}
+
 /// One line per HTTP request, so the web side shows up in the same log as the daemon.
 ///
 /// The log view polls `/api/logs`, so logging that path would generate a line per poll
@@ -1949,6 +1963,7 @@ async fn access_log(req: Request, next: Next) -> Response {
             otel.name = %format!("{method} {path}"),
             http.request.method = %method,
             url.path = %path,
+            http.route = tracing::field::Empty,
             http.response.status_code = tracing::field::Empty,
         )
     };