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>

CHANGELOG.md

@@ -39,6 +39,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 
+- The log has no terminal colour codes when it is not going to a terminal, as in `docker logs`.
 - A feed whose website names an icon that is missing shows the site's `/favicon.ico` instead of
   no artwork.
 - A website's icon standing in for a feed's artwork follows the site when it changes, and a