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/save_test.go

@@ -15,6 +15,7 @@ func TestSaveRestoreRoundTrip(t *testing.T) {
 	g.HasAmulet = true
 	g.Items.Potions[PotionHealing].Know = true
 	g.Items.Scrolls[ScrollMagicMapping].Guess = "map???"
+
 	g.Monsters['F'-'A'].Stats.Dmg = dice("3x1") // mutated bestiary must survive
 	if len(g.Level.Monsters) > 0 {
 		g.Level.Monsters[0].Flags.Set(Awake)
@@ -22,8 +23,10 @@ func TestSaveRestoreRoundTrip(t *testing.T) {
 	}
 
 	path := filepath.Join(t.TempDir(), "rogue.save")
-	if err := g.saveFile(path); err != nil {
-		t.Fatalf("saveFile: %v", err)
+
+	saveErr := g.saveFile(path)
+	if saveErr != nil {
+		t.Fatalf("saveFile: %v", saveErr)
 	}
 
 	h, err := Restore(path, Config{Term: &testTerm{}})
@@ -31,7 +34,8 @@ func TestSaveRestoreRoundTrip(t *testing.T) {
 		t.Fatalf("Restore: %v", err)
 	}
 
-	if _, err := os.Stat(path); !os.IsNotExist(err) {
+	_, statErr := os.Stat(path)
+	if !os.IsNotExist(statErr) {
 		t.Error("save file not deleted on restore (C anti-restart rule)")
 	}
 
@@ -39,36 +43,46 @@ func TestSaveRestoreRoundTrip(t *testing.T) {
 		t.Errorf("player state lost: purse=%d food=%d",
 			h.Player.Purse, h.Player.FoodLeft)
 	}
+
 	if !h.HasAmulet {
 		t.Error("amulet flag lost")
 	}
+
 	if !h.Items.Potions[PotionHealing].Know {
 		t.Error("potion identification lost")
 	}
+
 	if h.Items.Scrolls[ScrollMagicMapping].Guess != "map???" {
 		t.Error("scroll guess lost")
 	}
+
 	if h.Monsters['F'-'A'].Stats.Dmg.String() != "3x1" {
 		t.Error("mutated bestiary lost")
 	}
+
 	if h.Rng.Seed != g.Rng.Seed {
 		t.Error("RNG state lost")
 	}
+
 	if renderMap(h) != renderMap(g) {
 		t.Error("restored level map differs")
 	}
+
 	if len(h.Level.Monsters) != len(g.Level.Monsters) {
 		t.Fatalf("monster count %d != %d",
 			len(h.Level.Monsters), len(g.Level.Monsters))
 	}
+
 	if len(g.Level.Monsters) > 0 {
 		m := h.Level.Monsters[0]
 		if m.Dest != &h.Player.Pos {
 			t.Error("monster chase target not re-aliased to the hero")
 		}
+
 		if h.Level.MonsterAt(m.Pos.Y, m.Pos.X) != m {
 			t.Error("map monster index not rebuilt")
 		}
+
 		if m.Room == nil {
 			t.Error("monster room pointer not rebuilt")
 		}
@@ -81,13 +95,17 @@ func TestSaveRestoreRoundTrip(t *testing.T) {
 		len(st.Player.Body.Pack))
 	t.Logf("restored: CurWeapon=%p pack has %d items", h.Player.CurWeapon,
 		len(h.Player.Pack))
+
 	found := false
+
 	for i, o := range h.Player.Pack {
 		t.Logf("  pack[%d]=%p type=%v which=%d", i, o, o.Kind, o.Which)
+
 		if o == h.Player.CurWeapon {
 			found = true
 		}
 	}
+
 	if !found {
 		t.Error("restored CurWeapon is not aliased into the pack")
 	}
@@ -98,15 +116,24 @@ func TestRestoreRejectsWrongVersion(t *testing.T) {
 	path := filepath.Join(t.TempDir(), "rogue.save")
 	st := g.snapshot()
 	st.Version = "0.0.0"
-	f, err := os.Create(path)
+
+	f, err := os.Create(path) //nolint:gosec // G304: test temp path
 	if err != nil {
 		t.Fatal(err)
 	}
-	if err := gob.NewEncoder(f).Encode(st); err != nil {
-		t.Fatal(err)
+
+	encErr := gob.NewEncoder(f).Encode(st)
+	if encErr != nil {
+		t.Fatal(encErr)
 	}
-	f.Close()
-	if _, err := Restore(path, Config{}); err == nil {
+
+	closeErr := f.Close()
+	if closeErr != nil {
+		t.Fatal(closeErr)
+	}
+
+	_, restoreErr := Restore(path, Config{})
+	if restoreErr == nil {
 		t.Error("restore accepted an out-of-date save")
 	}
 }