Name Sentry transactions after the route they matched (closes #185)

sentryhttp names each transaction after the concrete path, which the
BeforeSendTransaction hook has to withhold, so with tracing on the
transactions would fall into one Sentry group per method, such as
POST /(redacted). A middleware installed beside every sentryhttp
handler now renames the transaction to the method and chi route
pattern once the request is routed, and sets its source to route. The
hook keeps a route-sourced name and withholds every other name as
before. A path that matches nothing at the top level keeps the
withheld name; one that matches no route inside a route group, or
that the group's middleware turns away, is named after the group's
pattern, such as GET /pages/*. Tracing stays off.

Model: opus-5-5

internal/server/export_test.go

@@ -91,6 +91,24 @@ func NewRouterForTest(
 	return s.router
 }
 
+// NewRouterWithSentryForTest is NewRouterForTest with the sentryhttp
+// handler registered, as a set SENTRY_DSN does in production.
+func NewRouterWithSentryForTest(
+	t *testing.T,
+	log *logger.Logger,
+	cfg *config.Config,
+	mw *middleware.Middleware,
+	h *handlers.Handlers,
+) http.Handler {
+	t.Helper()
+
+	s := newServerForTest(t, log, cfg, mw, h)
+	s.sentryEnabled.Store(true)
+	s.SetupRoutes()
+
+	return s.router
+}
+
 // ListenAddrForTest exposes the address the HTTP listener binds for
 // a given Config, so the rendering of host and port — IPv6
 // bracketing above all — can be pinned without standing up a