feat(server): скелет Go-сервера с healthz, readyz и api/v1/meta

- internal/config: конфигурация из env с валидацией и дефолтами (§5.1, §9.1)
- internal/httpx: middleware (request id, slog-логи, recover, security-заголовки),
  единый формат ошибок §8.5 и лимит тела запроса
- internal/database: SQLite WAL + busy_timeout + foreign_keys, один writer
  и пул чтения, goose-миграции embedded, PRAGMA optimize по расписанию
- internal/meta: полезная нагрузка /api/v1/meta (версия, фичи, лимиты)
- internal/server: маршруты, SPA-раздача собранного клиента, OpenAPI 3.1
- cmd/glchat: точка входа с graceful shutdown и JSON-логами
- тесты: конфиг, миграции и идемпотентность, HTTP-эндпоинты, статика, 404/405

internal/meta/meta_test.go

@@ -0,0 +1,65 @@
+package meta
+
+import (
+	"encoding/json"
+	"testing"
+
+	"glchat/internal/config"
+)
+
+func TestNewBuildsMetaPayload(t *testing.T) {
+	cfg := config.Config{
+		Domain:        "gl.mhspx.su",
+		FilesDomain:   "files.gl.mhspx.su",
+		InstanceName:  "glchat",
+		Version:       "v0.1.0",
+		Commit:        "abc1234",
+		BuildDate:     "2026-09-19T00:00:00Z",
+		MaxUploadSize: 26214400,
+	}
+
+	resp := New(cfg)
+	if resp.APIVersion != APIVersion {
+		t.Errorf("APIVersion = %q, want %q", resp.APIVersion, APIVersion)
+	}
+	if resp.BaseURL != "https://gl.mhspx.su" {
+		t.Errorf("BaseURL = %q", resp.BaseURL)
+	}
+	if resp.FilesURL != "https://files.gl.mhspx.su" {
+		t.Errorf("FilesURL = %q", resp.FilesURL)
+	}
+	if resp.GatewayURL != "wss://gl.mhspx.su/gateway" {
+		t.Errorf("GatewayURL = %q", resp.GatewayURL)
+	}
+	if resp.RTCPath != "/rtc" {
+		t.Errorf("RTCPath = %q", resp.RTCPath)
+	}
+	if resp.Version != "v0.1.0" || resp.Commit != "abc1234" {
+		t.Errorf("version metadata lost: %+v", resp)
+	}
+}
+
+func TestJSONUsesSnakeCaseKeys(t *testing.T) {
+	raw, err := json.Marshal(New(config.Config{Domain: "example.com", FilesDomain: "files.example.com"}))
+	if err != nil {
+		t.Fatalf("marshal meta: %v", err)
+	}
+	var decoded map[string]any
+	if err := json.Unmarshal(raw, &decoded); err != nil {
+		t.Fatalf("unmarshal meta: %v", err)
+	}
+	for _, key := range []string{"api_version", "base_url", "files_url", "gateway_url", "max_upload_size", "features"} {
+		if _, ok := decoded[key]; !ok {
+			t.Errorf("meta payload is missing key %q: %s", key, raw)
+		}
+	}
+	features, ok := decoded["features"].(map[string]any)
+	if !ok {
+		t.Fatalf("features is not an object: %s", raw)
+	}
+	for _, key := range []string{"registration_enabled", "anti_bot_enabled", "voice_enabled", "web_push_enabled", "oauth_enabled", "passkeys_enabled"} {
+		if _, ok := features[key]; !ok {
+			t.Errorf("features is missing key %q", key)
+		}
+	}
+}