fix(btw): 无 Postgres 时跳过旁路测试，go.mod 补 uuid 直接依赖

server/side_questions_test.go 的 fixture 在拿不到数据库配置时走 t.Fatal，
导致未设置 ARTEX_PG_DSN 的环境跑 go test ./server 直接失败，掩盖真实回归。
改为 t.Skipf，与 server 包其余测试一致。

db/side_questions.go 直接引用 github.com/google/uuid，go mod tidy 将其
从 indirect 移到 direct。

go.mod

@@ -5,6 +5,7 @@ go 1.26.3
 require (
 	github.com/Autumn-27/norma v0.3.7
 	github.com/golang-jwt/jwt/v5 v5.3.1
+	github.com/google/uuid v1.6.0
 	github.com/jackc/pgx/v5 v5.10.0
 	github.com/klauspost/compress v1.18.6
 	github.com/lqqyt2423/go-mitmproxy v1.9.2
@@ -24,7 +25,6 @@ require (
 	github.com/dustin/go-humanize v1.0.1 // indirect
 	github.com/gaissmai/bart v0.26.0 // indirect
 	github.com/golang/groupcache v0.0.0-20210331224755-41bb18bfe9da // indirect
-	github.com/google/uuid v1.6.0 // indirect
 	github.com/gorilla/css v1.0.1 // indirect
 	github.com/gorilla/websocket v1.5.3 // indirect
 	github.com/hinshun/vt10x v0.0.0-20220301184237-5011da428d02 // indirect

server/side_questions_test.go

@@ -142,7 +142,7 @@ func newSideHTTPFixture(t *testing.T) *sideHTTPFixture {
 	t.Helper()
 	m, err := NewManager(t.TempDir(), "")
 	if err != nil {
-		t.Fatal(err)
+		t.Skipf("postgres unavailable (%v) — skipping", err)
 	}
 	ctx, cancel := context.WithCancel(context.Background())
 	s := &Server{m: m, engine: NewEngine(m), ctx: ctx, jwtKey: []byte("btw-test-signing-key-only"), chatBusy: map[string]bool{}}