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.

game/fight_test.go

@@ -6,10 +6,12 @@ import "testing"
 // look() state the way playit() does before the first command.
 func mkGame(t *testing.T, seed int32) *RogueGame {
 	t.Helper()
+
 	g := NewGame(Config{Seed: seed, Term: &testTerm{}})
 	g.NewLevel()
 	g.Oldpos = g.Player.Pos
 	g.Oldrp = g.roomin(g.Player.Pos)
+
 	return g
 }
 
@@ -18,6 +20,7 @@ func spawnAdjacent(g *RogueGame, typ byte) *Monster {
 	pos := Coord{X: g.Player.Pos.X + 1, Y: g.Player.Pos.Y}
 	tp := &Monster{}
 	g.newMonster(tp, typ, pos)
+
 	return tp
 }
 
@@ -32,6 +35,7 @@ func TestRollEmParsesMultiAttackDice(t *testing.T) {
 	if !g.rollEm(att, def, nil, false) {
 		t.Fatal("attack with guaranteed swing missed")
 	}
+
 	dmg := 1000 - def.Stats.HP
 	if dmg < 6 || dmg > 15 {
 		t.Errorf("three 1x4+1 attacks dealt %d damage, want 6..15", dmg)
@@ -45,12 +49,15 @@ func TestFightKillsMonster(t *testing.T) {
 	g.Player.Stats.Lvl = 20 // always hits
 	before := len(g.Level.Monsters)
 	g.fight(tp.Pos, g.Player.CurWeapon, false)
+
 	if len(g.Level.Monsters) != before-1 {
 		t.Error("monster not removed after fatal fight")
 	}
+
 	if g.Level.MonsterAt(tp.Pos.Y, tp.Pos.X) != nil {
 		t.Error("map still records dead monster")
 	}
+
 	if g.Player.Stats.Exp == 0 {
 		t.Error("no experience for the kill")
 	}
@@ -61,10 +68,12 @@ func TestAttackHurtsPlayer(t *testing.T) {
 	tp := spawnAdjacent(g, 'T') // troll: 1x8/1x8/2x6
 	tp.Stats.Lvl = 20           // always hits
 	tp.Flags.Clear(Cancelled)
+
 	hpBefore := g.Player.Stats.HP
 	g.Player.Stats.HP = 500
 	g.Player.Stats.MaxHP = 500
 	g.attack(tp)
+
 	if g.Player.Stats.HP >= 500 {
 		t.Errorf("player HP unchanged (%d -> %d)", hpBefore, g.Player.Stats.HP)
 	}
@@ -72,15 +81,18 @@ func TestAttackHurtsPlayer(t *testing.T) {
 
 func TestDeathUnwindsWithGameEnd(t *testing.T) {
 	g := mkGame(t, 11)
+
 	defer func() {
 		r := recover()
 		if _, ok := r.(gameEnd); !ok {
 			t.Fatalf("death did not unwind with gameEnd, got %v", r)
 		}
+
 		if g.Playing {
 			t.Error("still playing after death")
 		}
 	}()
+
 	g.Options.Tombstone = false
 	g.death('K')
 }
@@ -90,16 +102,20 @@ func TestRunnersChaseHero(t *testing.T) {
 	// Place a hobgoblin a few squares away in the hero's room and set it
 	// running at the hero.
 	p := &g.Player
+
 	pos := Coord{X: p.Pos.X + 3, Y: p.Pos.Y}
 	if !stepOk(g.Level.Char(pos.Y, pos.X)) || g.Level.MonsterAt(pos.Y, pos.X) != nil {
 		t.Skip("no clear lane on this seed")
 	}
+
 	tp := &Monster{}
 	g.newMonster(tp, 'H', pos)
 	tp.Flags.Set(Awake)
 	tp.Dest = &p.Pos
 	d0 := distCp(tp.Pos, p.Pos)
+
 	g.runners(0)
+
 	if d1 := distCp(tp.Pos, p.Pos); d1 >= d0 {
 		t.Errorf("monster did not close distance: %d -> %d", d0, d1)
 	}