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/rng_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"
 // (seed = seed*11109+13849; rnd(range) = abs(RN) % range) compiled and run
 // on this machine. They lock in seed compatibility with the C game.
 func TestRndMatchesCImplementation(t *testing.T) {
+	t.Parallel()
+
 	golden := map[int32][]int{
 		1:          {0, 30, 79, 7, 87, 1, 23, 7, 57, 98},
 		12345:      {92, 92, 45, 98, 24, 39, 92, 67, 3, 7},
@@ -23,6 +26,8 @@ func TestRndMatchesCImplementation(t *testing.T) {
 }
 
 func TestRollMatchesCImplementation(t *testing.T) {
+	t.Parallel()
+
 	golden := map[int32][]int{
 		1:          {6, 8, 10},
 		12345:      {10, 10, 15},
@@ -42,6 +47,8 @@ func TestRollMatchesCImplementation(t *testing.T) {
 // rnd(0) must return 0 without stepping the generator: the C macro
 // short-circuits before evaluating RN, and BEFORE/AFTER depend on it.
 func TestRndZeroDoesNotStep(t *testing.T) {
+	t.Parallel()
+
 	r := &Rng{Seed: 42}
 	if got := r.Rnd(0); got != 0 {
 		t.Fatalf("rnd(0) = %d, want 0", got)
@@ -55,6 +62,8 @@ func TestRndZeroDoesNotStep(t *testing.T) {
 // spread(1)==1 and spread(2)==2 deterministically; the C BEFORE/AFTER
 // constants rely on this.
 func TestSpreadSmallValues(t *testing.T) {
+	t.Parallel()
+
 	g := &RogueGame{Rng: &Rng{Seed: 7}}
 	if got := g.spread(1); got != 1 {
 		t.Errorf("spread(1) = %d, want 1", got)