chore: initial commit of Go API gateway

Baseline for the Kong replacement on api.riotpiao.com. Brings the working
tree under version control for the first time: gateway source, the task
board that drives the agent runs, test fixtures, and K8s manifests.

Anchor the gateway ignore rule to the repo root. Unanchored, "gateway"
also matched the cmd/gateway/ source directory, so the program entrypoint
was excluded from every commit.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>

internal/config/auth_required_test.go

@@ -0,0 +1,24 @@
+package config_test
+
+import (
+	"testing"
+
+	"github.com/Riotpiaole/homelab-frontend/internal/config"
+)
+
+// TestLoadRoutesMissingAuthRequired tests that the auth-required flag is not a silent default:
+// if it is absent from YAML, startup must fail with a message naming the offending route and field.
+func TestLoadRoutesMissingAuthRequired(t *testing.T) {
+	routes, err := config.LoadRoutesFromFile("../../testdata/config/missing-authRequired.yaml")
+	if err == nil {
+		t.Fatal("expected error for missing authRequired, got nil")
+	}
+	if routes != nil {
+		t.Error("expected nil routes on error")
+	}
+	want := "route \"test-route\": field 'authRequired' is required"
+	got := err.Error()
+	if got != want {
+		t.Fatalf("error did not name the offending route and field; want %q, got %q", want, got)
+	}
+}