Re-vendor the shared files from sneak/prompts at 0653579 (closes #52)

Takes .golangci.yml, .dockerignore, .gitignore, .editorconfig, the
workflow and REPO_POLICIES.md from sneak/prompts 0653579, with this
repository's own entries after the shared content. Lint (golangci-lint
v2.14.0) and test are Dockerfile phases that script/lint and script/test
build alone with a new CACHEBUST value, keeping Go's and golangci-lint's
caches; the image build depends on both. make fmt and make fmt-check also
format the markdown with prettier, pinned in yarn.lock. The agent
guidance moves to AGENTS.md. The Go code is fixed for what the new
configuration finds, and the AS and prefix detail reads now return the
rows' error after their loops.

Model: opus-5-5

internal/server/server_test.go

@@ -1,4 +1,4 @@
-package server
+package server_test
 
 import (
 	"context"
@@ -8,6 +8,7 @@ import (
 	"git.eeqj.de/sneak/routewatch/internal/config"
 	"git.eeqj.de/sneak/routewatch/internal/logger"
 	"git.eeqj.de/sneak/routewatch/internal/metrics"
+	"git.eeqj.de/sneak/routewatch/internal/server"
 	"git.eeqj.de/sneak/routewatch/internal/streamer"
 )
 
@@ -16,18 +17,31 @@ import (
 // listened in a goroutine, only logged the failure and returned nil, so the
 // daemon kept running without its web server.
 func TestStartFailsWhenPortIsHeld(t *testing.T) {
-	held, err := net.Listen("tcp", ":0")
+	t.Parallel()
+
+	var listenConfig net.ListenConfig
+
+	held, err := listenConfig.Listen(t.Context(), "tcp", ":0")
 	if err != nil {
 		t.Fatalf("failed to open the test listener: %v", err)
 	}
 	defer func() { _ = held.Close() }()
 
-	port := held.Addr().(*net.TCPAddr).Port
+	addr, ok := held.Addr().(*net.TCPAddr)
+	if !ok {
+		t.Fatalf("test listener address %v is not a TCP address", held.Addr())
+	}
+
+	port := addr.Port
 	log := logger.New()
-	s := New(nil, streamer.New(log, metrics.New()), log, &config.Config{Port: port})
+	s := server.New(nil, streamer.New(log, metrics.New()), log,
+		&config.Config{Port: port})
+
 	defer func() { _ = s.Stop(context.Background()) }()
 
-	if err := s.Start(); err == nil {
-		t.Fatalf("Start returned nil while port %d was held by another listener", port)
+	err = s.Start(t.Context())
+	if err == nil {
+		t.Fatalf("Start returned nil while port %d was held by another listener",
+			port)
 	}
 }