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/route/stream.go

@@ -13,6 +13,7 @@ import (
 	"github.com/yusing/go-proxy/internal/route/routes"
 	"github.com/yusing/go-proxy/internal/route/stream"
 	"github.com/yusing/go-proxy/internal/task"
+	"github.com/yusing/go-proxy/internal/types"
 	"github.com/yusing/go-proxy/internal/watcher/health/monitor"
 )
 
@@ -24,7 +25,7 @@ type StreamRoute struct {
 	l zerolog.Logger
 }
 
-func NewStreamRoute(base *Route) (routes.Route, gperr.Error) {
+func NewStreamRoute(base *Route) (types.Route, gperr.Error) {
 	// TODO: support non-coherent scheme
 	return &StreamRoute{
 		Route: base,