chore: update golangci-lint to v2.12.2 with canonical config (#54)

Canonical v2-schema `.golangci.yml`, golangci-lint pins bumped to v2.12.2 in `Dockerfile` and `script/bootstrap`, and the tree brought to `0 issues.` under it.

Three behaviour deltas: `Cache.StoreVariant` takes a context (cancelled requests skip the accounting row, recovered by reconciliation); `MetadataStorage.Store` no longer leaks `.tmp-*.json` on Write/Close/Rename failure (dead-defer bug fix); the `signing_key` too-short error text gained a `value too short:` prefix.

Eviction-loop context cancellation deferred to #102.

internal/middleware/middleware.go

@@ -24,6 +24,7 @@ const CORSMaxAgeSeconds = 86400
 // Params defines dependencies for Middleware.
 type Params struct {
 	fx.In
+
 	Logger *logger.Logger
 	Config *config.Config
 }
@@ -49,6 +50,7 @@ func ipFromHostPort(hp string) string {
 	if err != nil {
 		return ""
 	}
+
 	if len(h) > 0 && h[0] == '[' {
 		return h[1 : len(h)-1]
 	}
@@ -58,6 +60,7 @@ func ipFromHostPort(hp string) string {
 
 type loggingResponseWriter struct {
 	http.ResponseWriter
+
 	statusCode   int
 	bytesWritten int64
 }
@@ -85,6 +88,7 @@ func (s *Middleware) Logging() func(http.Handler) http.Handler {
 			start := time.Now()
 			lrw := newLoggingResponseWriter(w)
 			ctx := r.Context()
+
 			defer func() {
 				latency := time.Since(start)
 				reqID, _ := ctx.Value(middleware.RequestIDKey).(string)

internal/middleware/middleware_internal_test.go

@@ -10,6 +10,8 @@ import (
 )
 
 func TestSecurityHeaders(t *testing.T) {
+	t.Parallel()
+
 	// Create middleware instance
 	cfg := &config.Config{}
 	mw := &Middleware{
@@ -26,7 +28,7 @@ func TestSecurityHeaders(t *testing.T) {
 	handler := mw.SecurityHeaders()(testHandler)
 
 	// Make a test request
-	req := httptest.NewRequest(http.MethodGet, "/test", nil)
+	req := httptest.NewRequestWithContext(t.Context(), http.MethodGet, "/test", nil)
 	rec := httptest.NewRecorder()
 
 	handler.ServeHTTP(rec, req)
@@ -44,6 +46,8 @@ func TestSecurityHeaders(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.header, func(t *testing.T) {
+			t.Parallel()
+
 			got := rec.Header().Get(tt.header)
 			if got != tt.want {
 				t.Errorf("%s = %q, want %q", tt.header, got, tt.want)
@@ -53,6 +57,8 @@ func TestSecurityHeaders(t *testing.T) {
 }
 
 func TestSecurityHeaders_PreservesExistingHeaders(t *testing.T) {
+	t.Parallel()
+
 	cfg := &config.Config{}
 	mw := &Middleware{
 		log:    slog.Default(),
@@ -68,7 +74,7 @@ func TestSecurityHeaders_PreservesExistingHeaders(t *testing.T) {
 
 	handler := mw.SecurityHeaders()(testHandler)
 
-	req := httptest.NewRequest(http.MethodGet, "/test", nil)
+	req := httptest.NewRequestWithContext(t.Context(), http.MethodGet, "/test", nil)
 	rec := httptest.NewRecorder()
 
 	handler.ServeHTTP(rec, req)