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/api/v1/favicon.go

@@ -0,0 +1,100 @@
+package v1
+
+import (
+	"context"
+	"net/http"
+
+	"github.com/gin-gonic/gin"
+	apitypes "github.com/yusing/go-proxy/internal/api/types"
+	"github.com/yusing/go-proxy/internal/homepage"
+	"github.com/yusing/go-proxy/internal/route/routes"
+)
+
+type GetFavIconRequest struct {
+	URL   string `form:"url" binding:"required_without=Alias"`
+	Alias string `form:"alias" binding:"required_without=URL"`
+} //	@name	GetFavIconRequest
+
+// GetFavIcon returns the favicon of the route
+//
+// Returns:
+//   - 200 OK: if icon found
+//   - 400 Bad Request: if alias is empty or route is not HTTPRoute
+//   - 404 Not Found: if route or icon not found
+//   - 500 Internal Server Error: if internal error
+//   - others: depends on route handler response
+
+// @x-id				"favicon"
+// @BasePath		/api/v1
+// @Summary		Get favicon
+// @Description	Get favicon
+// @Tags			v1
+// @Accept			json
+// @Produce		image/svg+xml,image/x-icon,image/png,image/webp
+// @Param			url		query		string	false	"URL of the route"
+// @Param			alias	query		string	false	"Alias of the route"
+// @Success		200		{array}		homepage.FetchResult
+// @Failure		400		{object}	apitypes.ErrorResponse
+// @Failure		403		{object}	apitypes.ErrorResponse
+// @Failure		404		{object}	apitypes.ErrorResponse
+// @Failure		500		{object}	apitypes.ErrorResponse
+// @Router			/favicon [get]
+func FavIcon(c *gin.Context) {
+	var request GetFavIconRequest
+	if err := c.ShouldBindQuery(&request); err != nil {
+		c.JSON(http.StatusBadRequest, apitypes.Error("invalid request", err))
+		return
+	}
+
+	// try with url
+	if request.URL != "" {
+		var iconURL homepage.IconURL
+		if err := iconURL.Parse(request.URL); err != nil {
+			c.JSON(http.StatusBadRequest, apitypes.Error("invalid url", err))
+			return
+		}
+		fetchResult := homepage.FetchFavIconFromURL(c.Request.Context(), &iconURL)
+		if !fetchResult.OK() {
+			c.JSON(fetchResult.StatusCode, apitypes.Error(fetchResult.ErrMsg))
+			return
+		}
+		c.Data(fetchResult.StatusCode, fetchResult.ContentType(), fetchResult.Icon)
+		return
+	}
+
+	// try with alias
+	result := GetFavIconFromAlias(c.Request.Context(), request.Alias)
+	if !result.OK() {
+		c.JSON(result.StatusCode, apitypes.Error(result.ErrMsg))
+		return
+	}
+	c.Data(result.StatusCode, result.ContentType(), result.Icon)
+}
+
+func GetFavIconFromAlias(ctx context.Context, alias string) *homepage.FetchResult {
+	// try with route.Icon
+	r, ok := routes.HTTP.Get(alias)
+	if !ok {
+		return &homepage.FetchResult{
+			StatusCode: http.StatusNotFound,
+			ErrMsg:     "route not found",
+		}
+	}
+
+	var result *homepage.FetchResult
+	hp := r.HomepageItem()
+	if hp.Icon != nil {
+		if hp.Icon.IconSource == homepage.IconSourceRelative {
+			result = homepage.FindIcon(ctx, r, *hp.Icon.FullURL)
+		} else {
+			result = homepage.FetchFavIconFromURL(ctx, hp.Icon)
+		}
+	} else {
+		// try extract from "link[rel=icon]"
+		result = homepage.FindIcon(ctx, r, "/")
+	}
+	if result.StatusCode == 0 {
+		result.StatusCode = http.StatusOK
+	}
+	return result
+}