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/object.go

@@ -5,6 +5,7 @@ package game
 // category (ObjectKind) from its display character (Glyph).
 type ObjectKind int
 
+// Item categories.
 const (
 	KindNone ObjectKind = iota
 	KindPotion
@@ -44,6 +45,7 @@ func (k ObjectKind) Glyph() byte {
 	if k < 0 || int(k) >= len(kindGlyphs) {
 		return ' '
 	}
+
 	return kindGlyphs[k]
 }
 
@@ -71,6 +73,7 @@ func (k ObjectKind) String() string {
 	case KindRingOrStick:
 		return "ring, wand or staff"
 	}
+
 	return "bizarre thing"
 }
 
@@ -82,6 +85,7 @@ func objectKindForGlyph(ch byte) ObjectKind {
 			return ObjectKind(k)
 		}
 	}
+
 	return KindNone
 }
 
@@ -148,6 +152,7 @@ func detachObj(list *[]*Object, item *Object) {
 	for i, o := range *list {
 		if o == item {
 			*list = append((*list)[:i], (*list)[i+1:]...)
+
 			return
 		}
 	}