Test that maintenance mode refuses image requests (closes #71)

Failing tests, ahead of the change: with maintenance_mode on, both image
routes must answer 503 with a Retry-After header and the JSON error body,
while the health check keeps answering 200 and reporting
maintenance_mode, and the login page and /metrics keep answering 200.
The test server now also builds the health check, which these tests
request.

Model: opus-5-5

internal/server/login_rate_limit_internal_test.go

@@ -18,6 +18,7 @@ import (
 	"sneak.berlin/go/pixa/internal/database"
 	"sneak.berlin/go/pixa/internal/globals"
 	"sneak.berlin/go/pixa/internal/handlers"
+	"sneak.berlin/go/pixa/internal/healthcheck"
 	"sneak.berlin/go/pixa/internal/logger"
 	"sneak.berlin/go/pixa/internal/middleware"
 )
@@ -70,8 +71,15 @@ func newTestServer(t *testing.T) *Server {
 		t.Fatalf("database.New() error = %v", err)
 	}
 
+	hc, err := healthcheck.New(lc, healthcheck.Params{
+		Globals: &globals.Globals{}, Config: cfg, Logger: log, Database: db,
+	})
+	if err != nil {
+		t.Fatalf("healthcheck.New() error = %v", err)
+	}
+
 	h, err := handlers.New(lc, handlers.Params{
-		Logger: log, Database: db, Config: cfg,
+		Logger: log, Healthcheck: hc, Database: db, Config: cfg,
 	})
 	if err != nil {
 		t.Fatalf("handlers.New() error = %v", err)