Adopt house golangci-lint config; fix all approved-linter findings

.golangci.yml is the prompts-repo standard verbatim plus one approved
exception (paralleltest, sneak 2026-07-06). Roughly 1,500 findings
fixed:

- autofix sweep (wsl_v5/nlreturn/intrange/modernize formatting), with
  the misspell autofix REVERTED where it rewrote authentic C game text
  ("missle vanishes" stays, with nolint and a comment)
- error handling: errcheck sites get real handling — saveFile now
  closes explicitly and removes corrupt saves, scoreboard writes are
  documented best-effort, err113 sentinel errors (ErrSaveOutOfDate,
  ErrScreenTooSmall); panics allowed for unrecoverable states per
  MEMORY.md policy
- gosec: real fixes (ParseInt for SEED, 0600 scorefile) and justified
  per-line nolints for provably-bounded conversions (randomMonsterLetter
  helper collapses eight rnd(26)+'A' sites)
- API tidying from linters: pointer receivers on flag types
  (recvcheck), msg helpers renamed addmsgf/doaddf/Printwf/MvPrintwf
  (goprintffuncname), myExit()/findFloor(monst)/mkGameInput(t) drop
  always-constant params (unparam), gameEnd carries no status
- gocritic/staticcheck: if-else chains to switches, the pack.c
  inventory filter untangled into matchesFilter, main.go split so
  defers run before exit (exitAfterDefer, funlen)
- revive doc comments on all exported flag types/consts/methods

Remaining findings are confined to linters pending sneak's exception
decision (mnd, gochecknoglobals, cyclop, nestif, gocognit, exhaustive,
goconst, testpackage); TODO.md records the state. MEMORY.md added at
repo root as the project's agent working notes.

cmd/rogue/main.go

@@ -18,61 +18,45 @@ import (
 )
 
 func main() {
+	os.Exit(run())
+}
+
+// run carries the real main so that deferred terminal restoration runs
+// before the process exits (os.Exit skips defers).
+func run() int {
 	scores := flag.Bool("s", false, "print the scoreboard and exit")
 	deathDemo := flag.Bool("d", false, "die a random death (demo)")
+
 	flag.Parse()
 
-	home, _ := os.UserHomeDir()
-
-	// get options from environment (main.c)
-	rogueOpts := os.Getenv("ROGUEOPTS")
-	name := ""
-	if u, err := user.Current(); err == nil {
-		name = u.Username
-	}
-
-	wizard := os.Getenv("ROGUE_WIZARD") != ""
-	// dungeon number: SEED for reproducible dungeons (wizard mode in C),
-	// else time+pid
-	var seed int32
-	if env := os.Getenv("SEED"); env != "" && wizard {
-		n, _ := strconv.Atoi(env)
-		seed = int32(n)
-	} else {
-		seed = int32(time.Now().Unix()) + int32(os.Getpid())
-	}
-
-	cfg := game.Config{
-		Seed:      seed,
-		Name:      name,
-		RogueOpts: rogueOpts,
-		Home:      home,
-		ScorePath: home + "/.rogue.scores",
-		Wizard:    wizard,
-	}
+	cfg := loadConfig()
 
 	if *scores {
-		g := game.NewGame(cfg)
-		g.ShowScores()
-		return
+		game.NewGame(cfg).ShowScores()
+
+		return 0
 	}
 
 	t, err := term.New()
 	if err != nil {
 		fmt.Fprintln(os.Stderr, err)
-		os.Exit(1)
+
+		return 1
 	}
 	defer t.Fini()
+
 	cfg.Term = t
 
 	var g *game.RogueGame
+
 	if args := flag.Args(); len(args) == 1 && !*deathDemo {
 		// restore a saved game
 		g, err = game.Restore(args[0], cfg)
 		if err != nil {
 			t.Fini()
 			fmt.Fprintln(os.Stderr, err)
-			os.Exit(1)
+
+			return 1
 		}
 	} else {
 		g = game.NewGame(cfg)
@@ -80,22 +64,75 @@ func main() {
 
 	if *deathDemo {
 		g.DeathDemo()
-		return
+
+		return 0
 	}
 
-	// SIGHUP/SIGTERM autosave (save.c auto_save)
+	installAutosave(g, t)
+
+	runErr := g.Run()
+	if runErr != nil {
+		t.Fini()
+		fmt.Fprintln(os.Stderr, runErr)
+
+		return 1
+	}
+
+	return 0
+}
+
+// loadConfig gathers the game configuration from the environment: home
+// directory, ROGUEOPTS, user name, wizard mode, and the dungeon seed
+// (main.c's startup).
+func loadConfig() game.Config {
+	home, _ := os.UserHomeDir()
+
+	name := ""
+
+	u, userErr := user.Current()
+	if userErr == nil {
+		name = u.Username
+	}
+
+	wizard := os.Getenv("ROGUE_WIZARD") != ""
+
+	return game.Config{
+		Seed:      chooseSeed(wizard),
+		Name:      name,
+		RogueOpts: os.Getenv("ROGUEOPTS"),
+		Home:      home,
+		ScorePath: home + "/.rogue.scores",
+		Wizard:    wizard,
+	}
+}
+
+// installAutosave saves the game and exits on SIGHUP/SIGTERM (save.c
+// auto_save).
+func installAutosave(g *game.RogueGame, t *term.Tcell) {
 	sig := make(chan os.Signal, 1)
+
 	signal.Notify(sig, syscall.SIGHUP, syscall.SIGTERM)
+
 	go func() {
 		<-sig
 		g.AutoSave()
 		t.Fini()
 		os.Exit(0)
 	}()
-
-	if err := g.Run(); err != nil {
-		t.Fini()
-		fmt.Fprintln(os.Stderr, err)
-		os.Exit(1)
-	}
+}
+
+// chooseSeed picks the dungeon number: SEED for reproducible dungeons
+// (wizard mode, as in the C game), else time+pid (main.c).
+func chooseSeed(wizard bool) int32 {
+	if env := os.Getenv("SEED"); env != "" && wizard {
+		n, err := strconv.ParseInt(env, 10, 32)
+		if err == nil {
+			return int32(n)
+		}
+	}
+
+	// The C game computed `lowtime + getpid()` in int; the truncation to
+	// 32 bits is the same wraparound the C int arithmetic performed.
+	return int32(time.Now().Unix()&0x7fffffff) + //nolint:gosec // G115: deliberate wrap
+		int32(os.Getpid()&0x7fffffff) //nolint:gosec // G115: deliberate wrap
 }