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/armor.go

@@ -5,36 +5,47 @@ package game
 // wear lets the player put armor on (armor.c wear).
 func (g *RogueGame) wear() {
 	p := &g.Player
+
 	obj := g.getItem("wear", KindArmor)
 	if obj == nil {
 		return
 	}
+
 	if p.CurArmor != nil {
-		g.addmsg("you are already wearing some")
+		g.addmsgf("you are already wearing some")
+
 		if !g.Options.Terse {
-			g.addmsg(".  You'll have to take it off first")
+			g.addmsgf(".  You'll have to take it off first")
 		}
+
 		g.endmsg()
 		g.After = false
+
 		return
 	}
+
 	if obj.Kind != KindArmor {
 		g.msg("you can't wear that")
+
 		return
 	}
+
 	g.wasteTime()
 	obj.Flags.Set(Known)
 	sp := g.invName(obj, true)
 	p.CurArmor = obj
+
 	if !g.Options.Terse {
-		g.addmsg("you are now ")
+		g.addmsgf("you are now ")
 	}
+
 	g.msg("wearing %s", sp)
 }
 
 // takeOff gets the armor off of the player's back (armor.c take_off).
 func (g *RogueGame) takeOff() {
 	p := &g.Player
+
 	obj := p.CurArmor
 	if obj == nil {
 		g.After = false
@@ -43,17 +54,22 @@ func (g *RogueGame) takeOff() {
 		} else {
 			g.msg("you aren't wearing any armor")
 		}
+
 		return
 	}
+
 	if !g.dropCheck(p.CurArmor) {
 		return
 	}
+
 	p.CurArmor = nil
+
 	if g.Options.Terse {
-		g.addmsg("was")
+		g.addmsgf("was")
 	} else {
-		g.addmsg("you used to be")
+		g.addmsgf("you used to be")
 	}
+
 	g.msg(" wearing %c) %s", obj.PackCh, g.invName(obj, true))
 }