Re-vendor the shared files from sneak/prompts at dd4027b (closes #52)

Takes .golangci.yml, .dockerignore, .gitignore, .editorconfig, the
workflow and REPO_POLICIES.md from sneak/prompts dd4027b, keeping this
repository's own entries after the shared content. Lint (golangci-lint
v2.14.0) and test become Dockerfile phases that script/lint and
script/test build alone and uncached; the image build depends on both,
and script/cibuild bootstraps, runs script/check, then builds the image.
The agent guidance file moves to AGENTS.md. The Go code is fixed for
what the new configuration finds; reads that iterate rows now also
report an iteration error.

Model: opus-5-5

internal/server/server.go

@@ -3,6 +3,7 @@ package server
 
 import (
 	"context"
+	"errors"
 	"net/http"
 	"strconv"
 	"time"
@@ -40,7 +41,12 @@ 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,
@@ -76,7 +82,9 @@ func (s *Server) Start() error {
 	// Start in goroutine but log when actually listening
 	go func() {
 		s.logger.Info("HTTP server listening", "addr", s.srv.Addr)
-		if err := s.srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
+
+		err := s.srv.ListenAndServe()
+		if err != nil && !errors.Is(err, http.ErrServerClosed) {
 			s.logger.Error("HTTP server error", "error", err)
 		}
 	}()