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/watcher/health/monitor/fileserver.go

@@ -4,7 +4,7 @@ import (
 	"os"
 	"time"
 
-	"github.com/yusing/go-proxy/internal/watcher/health"
+	"github.com/yusing/go-proxy/internal/types"
 )
 
 type FileServerHealthMonitor struct {
@@ -12,24 +12,24 @@ type FileServerHealthMonitor struct {
 	path string
 }
 
-func NewFileServerHealthMonitor(config *health.HealthCheckConfig, path string) *FileServerHealthMonitor {
+func NewFileServerHealthMonitor(config *types.HealthCheckConfig, path string) *FileServerHealthMonitor {
 	mon := &FileServerHealthMonitor{path: path}
 	mon.monitor = newMonitor(nil, config, mon.CheckHealth)
 	return mon
 }
 
-func (s *FileServerHealthMonitor) CheckHealth() (*health.HealthCheckResult, error) {
+func (s *FileServerHealthMonitor) CheckHealth() (*types.HealthCheckResult, error) {
 	start := time.Now()
 	_, err := os.Stat(s.path)
 	if err != nil {
 		if os.IsNotExist(err) {
-			return &health.HealthCheckResult{
+			return &types.HealthCheckResult{
 				Detail: err.Error(),
 			}, nil
 		}
 		return nil, err
 	}
-	return &health.HealthCheckResult{
+	return &types.HealthCheckResult{
 		Healthy: true,
 		Latency: time.Since(start),
 	}, nil