lua: 吸收 llmsproxy 适配器高级特性（worker 池/静态预提取/动态签名钩子）

- 适配器 worker 池化：单 LState+全局锁（串行瓶颈）→ 每 adapter 一个 gopher-lua
  LState 池，按使用该 adapter 的源并发上限求和配置池大小，并发 transform 互不阻塞
- staticInfo 预提取：name/version/endpoint/headers 加载期编译缓存，Endpoint/Headers
  读缓存不占 worker；加载即预编译首个 worker
- build_headers 动态钩子 + hmac/sha256/base64/tohex 全局：签名型上游（kimicode 等）可接入
- provider applyAdapterHeaders 接入动态头（url/method/body/api_key/timestamp/source 元数据），
  未定义时回落静态 headers，缺省补 Authorization
- LLMSource.MaxConcurrent + core.llm.sources.<name>.max_concurrent，注册时汇总
  VM.ConfigureConcurrency
- 新增 Lua VM 测试（load/transform/build_headers/并发）

验证: go test ./... 27 包 0 失败；Windows 交叉编译通过；部署后 9 adapter 全部预加载

internal/lua/vm_test.go

@@ -0,0 +1,137 @@
+package lua
+
+import (
+	"strings"
+	"sync"
+	"testing"
+)
+
+func TestVMLoadAndTransform(t *testing.T) {
+	vm := NewVM(t.TempDir())
+	if err := vm.Start(); err != nil {
+		t.Fatalf("start vm: %v", err)
+	}
+	defer vm.Stop()
+
+	out, err := vm.CallTransformRequest("openai", `{"model":"x"}`)
+	if err != nil {
+		t.Fatalf("transform_request: %v", err)
+	}
+	if !strings.Contains(out, `"model":"x"`) {
+		t.Fatalf("unexpected output: %s", out)
+	}
+
+	ep := vm.GetAdapterEndpoint("openai")
+	if ep == "" {
+		t.Fatal("openai endpoint empty")
+	}
+	hdrs := vm.GetAdapterHeaders("openai")
+	if hdrs == nil {
+		t.Fatal("openai headers nil")
+	}
+}
+
+func TestVMLoadCustomAdapter(t *testing.T) {
+	vm := NewVM(t.TempDir())
+	if err := vm.Start(); err != nil {
+		t.Fatalf("start vm: %v", err)
+	}
+	defer vm.Stop()
+
+	code := `
+local adapter = {}
+adapter.name = "testa"
+adapter.version = "1.0"
+adapter.endpoint = "/x"
+adapter.headers = { ["X-A"] = "1" }
+function adapter.transform_request(raw) return "REQ" end
+function adapter.build_headers(meta) return { ["X-Key"] = "k" } end
+function adapter.transform_response(raw) return "RESP" end
+function adapter.transform_stream_chunk(raw) return "CHUNK" end
+return adapter
+`
+	if err := vm.LoadAdapterSource("testa", code); err != nil {
+		t.Fatalf("load adapter: %v", err)
+	}
+
+	if out, err := vm.CallTransformRequest("testa", "x"); err != nil || out != "REQ" {
+		t.Fatalf("req=%q err=%v", out, err)
+	}
+	if out, err := vm.CallTransformResponse("testa", "x"); err != nil || out != "RESP" {
+		t.Fatalf("resp=%q err=%v", out, err)
+	}
+	if out, err := vm.CallTransformStreamChunk("testa", "x"); err != nil || out != "CHUNK" {
+		t.Fatalf("chunk=%q err=%v", out, err)
+	}
+
+	meta := map[string]interface{}{"url": "http://x", "api_key": "k1"}
+	hdrs, err := vm.BuildHeaders("testa", meta)
+	if err != nil {
+		t.Fatalf("build_headers: %v", err)
+	}
+	if hdrs["X-Key"] != "k" {
+		t.Fatalf("missing dynamic header: %v", hdrs)
+	}
+
+	if ep := vm.GetAdapterEndpoint("testa"); ep != "/x" {
+		t.Fatalf("endpoint=%q", ep)
+	}
+	if st := vm.GetAdapterHeaders("testa"); st["X-A"] != "1" {
+		t.Fatalf("static headers=%v", st)
+	}
+}
+
+func TestVMLoadStaticHeaderFallback(t *testing.T) {
+	vm := NewVM(t.TempDir())
+	if err := vm.Start(); err != nil {
+		t.Fatalf("start vm: %v", err)
+	}
+	defer vm.Stop()
+
+	code := `
+local adapter = {}
+adapter.name = "statics"
+adapter.headers = { ["X-S"] = "s" }
+function adapter.transform_request(raw) return raw end
+return adapter
+`
+	if err := vm.LoadAdapterSource("statics", code); err != nil {
+		t.Fatalf("load: %v", err)
+	}
+	hdrs, err := vm.BuildHeaders("statics", nil)
+	if err != nil {
+		t.Fatalf("build_headers: %v", err)
+	}
+	if hdrs["X-S"] != "s" {
+		t.Fatalf("expected static fallback, got %v", hdrs)
+	}
+}
+
+func TestVMConcurrentCalls(t *testing.T) {
+	vm := NewVM(t.TempDir())
+	if err := vm.Start(); err != nil {
+		t.Fatalf("start vm: %v", err)
+	}
+	defer vm.Stop()
+
+	var wg sync.WaitGroup
+	errs := make(chan error, 40)
+	for i := 0; i < 20; i++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			for j := 0; j < 10; j++ {
+				_, err := vm.CallTransformRequest("openai", `{"model":"x"}`)
+				if err != nil {
+					errs <- err
+					return
+				}
+			}
+		}()
+	}
+	wg.Wait()
+	close(errs)
+	for err := range errs {
+		t.Fatalf("concurrent call: %v", err)
+	}
+}