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/tables.go

@@ -206,7 +206,7 @@ var sylls = []string{
 	"prok", "re", "rea", "rhov", "ri", "ro", "rog", "rok", "rol", "sa",
 	"san", "sat", "sef", "seh", "shu", "ski", "sna", "sne", "snik",
 	"sno", "so", "sol", "sri", "sta", "sun", "ta", "tab", "tem",
-	"ther", "ti", "tox", "trol", "tue", "turs", "u", "ulk", "um", "un",
+	"there", "ti", "tox", "trol", "tue", "turs", "u", "ulk", "um", "un",
 	"uni", "ur", "val", "viv", "vly", "vom", "wah", "wed", "werg",
 	"wex", "whon", "wun", "xo", "y", "yot", "yu", "zant", "zeb", "zim",
 	"zok", "zon", "zum",