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/logbound_test.go

@@ -10,8 +10,10 @@ package middleware_test
 //     the client's choosing.
 //   - CSRF's 403 rejection, at WARN, also registered ahead of
 //     RequireAuth.
-//   - The rate limiters' 429 rejection, at WARN, on the
-//     unauthenticated receiver among others.
+//   - The rate limiters' 429 rejection, at WARN. On the receiver
+//     route it names the route pattern rather than the path, and
+//     the limiters that log a path sit behind RequireAuth, so its cap
+//     is defensive.
 //   - RequireAuth's own unauthenticated-request line, at DEBUG.
 //   - RecordLoginFailure's throttle rejection, at WARN. Its cap is
 //     defensive rather than load-bearing today: chi pins the one
@@ -268,10 +270,14 @@ func logSites() map[string]logSite {
 			send:       postNoToken,
 			wantStatus: http.StatusForbidden,
 		},
-		// The per-entrypoint receiver limiter, unauthenticated. Its
-		// bucket is keyed on the path, so the first request through a
-		// fresh path is served and only the ones after it are
-		// rejected; sendUntilLimited absorbs that.
+		// The 429 line every limiter but the aggregate one shares.
+		// Mounted outside any route, as here, it logs the path, as
+		// it does for the limiters behind RequireAuth; on
+		// ReceiverRoute it names the pattern instead. The
+		// per-entrypoint receiver limiter's bucket is keyed on the
+		// path, so the first request through a fresh path is served
+		// and only the ones after it are rejected; sendUntilLimited
+		// absorbs that.
 		"receiver rate limit 429": {
 			build: func(
 				t *testing.T, m *middleware.Middleware,