chore(lint): adopt canonical golangci-lint config

Replace .golangci.yml with the shared canonical config. The old
config's top-level linters-settings block was silently ignored under
the v2 schema, so the lll/funlen/cyclop/dupl thresholds now actually
apply. The four repo-specific disables (mnd, exhaustive, paralleltest,
testpackage) move out of the config into targeted in-code nolint
directives carrying their original approval dates, keeping the config
byte-identical to the canonical one.

Fixes surfaced by the stricter settings: t.Parallel() added to all 32
tests, 24 overlong lines wrapped or their comments tightened, tcell
control-code returns rewritten as character literals, dupl markers on
the identically-shaped item data tables, and two wsl_v5 defer cuddles.

No behavior changes. The repo has no golangci-lint version pin (no
Dockerfile or CI; make lint runs the host binary, currently v2.12.2),
so there was nothing to bump.

game/dice_test.go

@@ -1,3 +1,4 @@
+//nolint:testpackage // white-box tests reach unexported state (approved 2026-07-07)
 package game
 
 import "testing"
@@ -6,6 +7,8 @@ import "testing"
 // including its junk-tolerant edges: the bestiary placeholder "%%%x0" and
 // the flytrap reset "000x0" both mean a single 0x0 attack.
 func TestParseDice(t *testing.T) {
+	t.Parallel()
+
 	cases := []struct {
 		in   string
 		want string
@@ -32,6 +35,8 @@ func TestParseDice(t *testing.T) {
 // The bestiary and weapon tables must parse to at least one attack each so
 // every creature and weapon actually swings.
 func TestTablesHaveDice(t *testing.T) {
+	t.Parallel()
+
 	data := newGameData()
 	for i, m := range data.monsterTable {
 		if len(m.Stats.Dmg) == 0 {