refactor(api): restructured API for type safety, maintainability and docs generation

- These changes makes the API incombatible with previous versions
- Added new types for error handling, success responses, and health checks.
- Updated health check logic to utilize the new types for better clarity and structure.
- Refactored existing handlers to improve response consistency and error handling.
- Updated Makefile to include a new target for generating API types from Swagger.
- Updated "new agent" API to respond an encrypted cert pair

internal/net/gphttp/loadbalancer/server.go

@@ -0,0 +1,72 @@
+package loadbalancer
+
+import (
+	"net/http"
+
+	idlewatcher "github.com/yusing/go-proxy/internal/idlewatcher/types"
+	nettypes "github.com/yusing/go-proxy/internal/net/types"
+	"github.com/yusing/go-proxy/internal/types"
+	U "github.com/yusing/go-proxy/internal/utils"
+)
+
+type server struct {
+	_ U.NoCopy
+
+	name   string
+	url    *nettypes.URL
+	weight int
+
+	http.Handler `json:"-"`
+	types.HealthMonitor
+}
+
+func NewServer(name string, url *nettypes.URL, weight int, handler http.Handler, healthMon types.HealthMonitor) types.LoadBalancerServer {
+	srv := &server{
+		name:          name,
+		url:           url,
+		weight:        weight,
+		Handler:       handler,
+		HealthMonitor: healthMon,
+	}
+	return srv
+}
+
+func TestNewServer[T ~int | ~float32 | ~float64](weight T) types.LoadBalancerServer {
+	srv := &server{
+		weight: int(weight),
+		url:    nettypes.MustParseURL("http://localhost"),
+	}
+	return srv
+}
+
+func (srv *server) Name() string {
+	return srv.name
+}
+
+func (srv *server) URL() *nettypes.URL {
+	return srv.url
+}
+
+func (srv *server) Key() string {
+	return srv.url.Host
+}
+
+func (srv *server) Weight() int {
+	return srv.weight
+}
+
+func (srv *server) SetWeight(weight int) {
+	srv.weight = weight
+}
+
+func (srv *server) String() string {
+	return srv.name
+}
+
+func (srv *server) TryWake() error {
+	waker, ok := srv.Handler.(idlewatcher.Waker)
+	if ok {
+		return waker.Wake()
+	}
+	return nil
+}