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.

TODO.md

@@ -34,6 +34,19 @@ wizard commands).
 
 # Completed Steps
 
+- 2026-08-07 Canonical linter config (`golangci-v2.12.2`): replaced
+  `.golangci.yml` with the shared canonical config (v2 schema; settings now live
+  under `linters.settings`, so the `lll`/`funlen`/`cyclop`/`dupl` thresholds
+  actually apply — the old top-level `linters-settings` block was silently
+  ignored). The four repo-specific disables (`mnd`, `exhaustive`,
+  `paralleltest`, `testpackage`) moved out of the config into targeted in-code
+  `//nolint` directives carrying the original approval dates, so the config
+  stays byte-identical to canonical. Real fixes: `t.Parallel()` in all 32 tests,
+  24 long lines wrapped or their comments tightened, control bytes in
+  `term/tcell.go` as character literals, and two `wsl_v5` defer cuddles. The
+  repo has no golangci-lint version pin to bump (no Dockerfile or CI;
+  `make lint` runs the host `golangci-lint`, currently v2.12.2).
+
 - 2026-07-24 Seed compatibility — item tables (seed-compat): instrumented the C
   reference on modern-rogue with a DUMP mode (testdata/c_seedcompat.patch) that
   forces the RNG seed and prints the per-seed item appearance tables (potion