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

cmd/asinfo-gen/main.go

@@ -2,8 +2,10 @@
 package main
 
 import (
+	"context"
 	"encoding/csv"
 	"encoding/json"
+	"errors"
 	"io"
 	"log"
 	"net/http"
@@ -27,13 +29,17 @@ func main() {
 
 	// Fetch the CSV data
 	log.Println("Fetching AS CSV data...")
-	resp, err := http.Get(asCsvURL)
+
+	req, err := http.NewRequestWithContext(
+		context.Background(), http.MethodGet, asCsvURL, nil)
+	if err != nil {
+		log.Fatalf("Failed to fetch CSV: %v", err)
+	}
+
+	resp, err := http.DefaultClient.Do(req)
 	if err != nil {
 		log.Fatalf("Failed to fetch CSV: %v", err)
 	}
-	defer func() {
-		_ = resp.Body.Close()
-	}()
 
 	if resp.StatusCode != http.StatusOK {
 		log.Fatalf("Failed to fetch CSV: HTTP %d", resp.StatusCode)
@@ -48,17 +54,20 @@ func main() {
 		log.Fatalf("Failed to read CSV header: %v", err)
 	}
 
-	if len(header) != 3 || header[0] != "asn" || header[1] != "handle" || header[2] != "description" {
+	if len(header) != 3 || header[0] != "asn" || header[1] != "handle" ||
+		header[2] != "description" {
 		log.Fatalf("Unexpected CSV header: %v", header)
 	}
 
 	// Read all records
 	var asInfos []ASInfo
+
 	for {
 		record, err := reader.Read()
-		if err == io.EOF {
+		if errors.Is(err, io.EOF) {
 			break
 		}
+
 		if err != nil {
 			log.Printf("Error reading CSV record: %v", err)
 
@@ -86,12 +95,18 @@ func main() {
 		})
 	}
 
+	// Closed here rather than deferred: log.Fatalf exits without running
+	// deferred calls.
+	_ = resp.Body.Close()
+
 	log.Printf("Parsed %d AS records", len(asInfos))
 
 	// Convert to JSON and output to stdout
 	encoder := json.NewEncoder(os.Stdout)
 	encoder.SetIndent("", "\t")
-	if err := encoder.Encode(asInfos); err != nil {
+
+	err = encoder.Encode(asInfos)
+	if err != nil {
 		log.Fatalf("Failed to encode JSON: %v", err)
 	}
 }

cmd/streamdumper/main.go

@@ -26,9 +26,17 @@ func main() {
 
 	// Register raw message handler that prints to stdout
 	s.RegisterRawHandler(func(line string) {
-		fmt.Println(line)
+		_, _ = fmt.Fprintln(os.Stdout, line)
 	})
 
+	// Start streaming before any defer: log.Fatal exits without running
+	// deferred calls.
+	err := s.Start(context.Background())
+	if err != nil {
+		log.Fatal("Failed to start streamer:", err)
+	}
+	defer s.Stop()
+
 	// Set up context with cancellation
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
@@ -36,18 +44,13 @@ func main() {
 	// Handle signals
 	sigChan := make(chan os.Signal, 1)
 	signal.Notify(sigChan, os.Interrupt, syscall.SIGTERM)
+
 	go func() {
 		<-sigChan
 		log.Println("Received shutdown signal")
 		cancel()
 	}()
 
-	// Start streaming
-	if err := s.Start(); err != nil {
-		log.Fatal("Failed to start streamer:", err)
-	}
-	defer s.Stop()
-
 	// Wait for context cancellation
 	<-ctx.Done()
 }