Keep the entrypoint UUID out of webhooker's own logs (closes #531)

On the receiver route the access log and the per-entrypoint 429 line
name the route pattern whatever the status. The received line names
the entrypoint and webhook IDs, and the unknown-entrypoint line logs
no path. The pattern is middleware.ReceiverRoute, which routes.go
registers the receiver with.

The README says the proxy's access log holds the UUID and must be
protected like the URL, and its access-log, rate-limit, Sentry and
log-size passages now match the code.

Model: opus-5-5

internal/middleware/ratelimit.go

@@ -259,26 +259,28 @@ func (m *Middleware) clientAddr(r *http.Request) (netip.Addr, bool) {
 	return peer, true
 }
 
-// tooManyRequests returns the 429 handler used by the
-// password-change and per-entrypoint receiver limiters: it logs the
+// tooManyRequests returns the 429 handler used by the postRateLimit
+// limiters and the per-entrypoint receiver limiter: it logs the
 // rejection with logMessage and answers with responseMessage.
 // httprate adds the Retry-After header (RFC 6585). The aggregate
 // receiver limiter uses floodTooManyRequests instead.
 //
-// The path is capped against the same budget as the access log's url
-// field. The per-entrypoint receiver limiter is unauthenticated and
-// its path is a client-chosen segment of client-chosen length, so at
-// WARN an uncapped path would let a sender pick the size of the line
-// it writes — the same defect the access log capping closed.
+// On ReceiverRoute the line names the route pattern, so the
+// entrypoint UUID in the path is never logged. Elsewhere it names the
+// path, capped against the same budget as the access log's url field;
+// the limiters there sit behind RequireAuth, so the cap is defensive.
 func (m *Middleware) tooManyRequests(
 	logMessage, responseMessage string,
 ) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
+		path := r.URL.Path
+		if routePatternID(r.Context()) == ReceiverRoute {
+			path = ReceiverRoute
+		}
+
 		m.log.Warn(
 			logMessage,
-			"path", logfield.Truncate(
-				r.URL.Path, logfield.MaxBytes,
-			),
+			"path", logfield.Truncate(path, logfield.MaxBytes),
 			"remoteIP", RemoteIP(r),
 			"clientIP", ClientIP(r),
 		)