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.go

@@ -3,6 +3,7 @@ package server
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"net"
 	"net/http"
@@ -42,7 +43,12 @@ type Server struct {
 }
 
 // New creates a new HTTP server
-func New(db database.Store, streamer *streamer.Streamer, logger *logger.Logger, cfg *config.Config) *Server {
+func New(
+	db database.Store,
+	streamer *streamer.Streamer,
+	logger *logger.Logger,
+	cfg *config.Config,
+) *Server {
 	s := &Server{
 		db:       db,
 		streamer: streamer,
@@ -57,8 +63,8 @@ func New(db database.Store, streamer *streamer.Streamer, logger *logger.Logger,
 
 // Start listens on the configured port and serves HTTP in the background.
 // It returns an error if it cannot listen, for example because the port is
-// already in use.
-func (s *Server) Start() error {
+// already in use. ctx bounds only opening the port, not serving.
+func (s *Server) Start(ctx context.Context) error {
 	const (
 		network           = "tcp"
 		readHeaderTimeout = 40 * time.Second
@@ -78,7 +84,9 @@ func (s *Server) Start() error {
 
 	s.logger.Info("Starting HTTP server", "port", s.port, "addr", s.srv.Addr)
 
-	listener, err := net.Listen(network, s.srv.Addr)
+	var listenConfig net.ListenConfig
+
+	listener, err := listenConfig.Listen(ctx, network, s.srv.Addr)
 	if err != nil {
 		return fmt.Errorf("starting HTTP server: %w", err)
 	}
@@ -86,7 +94,8 @@ func (s *Server) Start() error {
 	s.logger.Info("HTTP server listening", "addr", listener.Addr().String())
 
 	go func() {
-		if err := s.srv.Serve(listener); err != nil && err != http.ErrServerClosed {
+		err := s.srv.Serve(listener)
+		if err != nil && !errors.Is(err, http.ErrServerClosed) {
 			s.logger.Error("HTTP server error", "error", err)
 		}
 	}()