Skip live network feed test under -short for deterministic make check (closes #2)

TestRouteWatchLiveFeed streams the live RIPE RIS feed for about five
seconds, which made make check nondeterministic and network-dependent.
Guard it with a testing.Short() skip and pass -short in both go test
lines of script/test, so the default suite runs offline and
deterministically. The README documents how to run the live test on
demand.

Test-only change; no production behavior changes.

Model: opus-4-8

README.md

@@ -204,7 +204,9 @@ them. We provide:
 - `script/projectname` — print the project name (used for the Docker
   image tag)
 - `script/test` — run the test suite
-  (`go test -timeout 30s -race -cover ./...`, verbose rerun on failure)
+  (`go test -short -timeout 30s -race -cover ./...`, verbose rerun on
+  failure). The `-short` flag skips the live-network integration test so the
+  default run is deterministic and offline.
 - `script/lint` — run `go vet ./...` and `golangci-lint run`
 - `script/fmt` — format all code (writes)
 - `script/fmt-check` — check formatting (read-only)
@@ -218,6 +220,11 @@ them. We provide:
 - `script/install-precommit` — install the git pre-commit hook that
   runs `script/precommit`
 
+The live-network integration test `TestRouteWatchLiveFeed` streams the RIPE
+RIS feed for a few seconds and is skipped in short mode. To run it on demand,
+invoke `go test` directly without `-short`:
+`go test -run TestRouteWatchLiveFeed ./internal/routewatch/`.
+
 ## License
 
 See LICENSE file.