feat(canvas): 画布工作区 - 整合侧栏与风格预设并修复提示词回填

选择性整合 #547，保留主分支节点与工具条设计。新增默认折叠的节点、资产、任务和历史面板，风格与预设保留在节点内，移除重复入口。

补齐工具权限、提示词解析、资源引用保护及数据库迁移，修复提示词清空和连续编辑后的生成配置同步。

验证：前端全量 1925 项测试、构建、类型检查及 lint 通过；后端 go test ./... 通过。真实模型、PostgreSQL 实库与登录态页面验收仍待进行。

Refs #547

Co-authored-by: bensharp <bensharp@qq.com>

backend/internal/handler/tools.go

@@ -0,0 +1,137 @@
+package handler
+
+import (
+	"net/http"
+	"strconv"
+
+	"infinite-canvas/backend/internal/service"
+
+	"github.com/gin-gonic/gin"
+)
+
+// RegisterToolRoutes 注册画布工具 API：查询、收藏、新增、删除。
+func RegisterToolRoutes(r *gin.RouterGroup, svc *service.Service) {
+	r.GET("/tools", func(c *gin.Context) {
+		user, err := currentUser(c, svc)
+		if err != nil {
+			failService(c, err)
+			return
+		}
+		page, pageSize, err := parsePaginationQuery(c, 20)
+		if err != nil {
+			fail(c, http.StatusBadRequest, err)
+			return
+		}
+		result, err := svc.Tools(user.ID, service.ToolListRequest{
+			Page:     page,
+			PageSize: pageSize,
+			Scope:    c.DefaultQuery("scope", "public"),
+			Type:     c.Query("type"),
+			Tag:      c.Query("tag"),
+			Search:   c.Query("search"),
+		})
+		if err != nil {
+			failService(c, err)
+			return
+		}
+		ok(c, result)
+	})
+
+	r.GET("/tools/:id", func(c *gin.Context) {
+		user, err := currentUser(c, svc)
+		if err != nil {
+			failService(c, err)
+			return
+		}
+		toolID, err := parseToolID(c)
+		if err != nil {
+			fail(c, http.StatusBadRequest, err)
+			return
+		}
+		item, err := svc.ToolDetail(user.ID, toolID)
+		if err != nil {
+			failService(c, err)
+			return
+		}
+		ok(c, item)
+	})
+
+	r.POST("/tools", func(c *gin.Context) {
+		user, err := currentUser(c, svc)
+		if err != nil {
+			failService(c, err)
+			return
+		}
+		c.Request.Body = http.MaxBytesReader(c.Writer, c.Request.Body, 64<<10)
+		var req service.ToolMutationRequest
+		if err := c.ShouldBindJSON(&req); err != nil {
+			failService(c, service.BadAuthRequest("请求体格式无效"))
+			return
+		}
+		item, err := svc.CreateTool(user.ID, req)
+		if err != nil {
+			failService(c, err)
+			return
+		}
+		ok(c, item)
+	})
+
+	r.POST("/tools/:id/favorite", func(c *gin.Context) {
+		setToolFavorite(c, svc, true)
+	})
+
+	r.DELETE("/tools/:id/favorite", func(c *gin.Context) {
+		setToolFavorite(c, svc, false)
+	})
+
+	r.DELETE("/tools/:id", func(c *gin.Context) {
+		user, err := currentUser(c, svc)
+		if err != nil {
+			failService(c, err)
+			return
+		}
+		toolID, err := parseToolID(c)
+		if err != nil {
+			fail(c, http.StatusBadRequest, err)
+			return
+		}
+		if err := svc.DeleteTool(user.ID, toolID); err != nil {
+			failService(c, err)
+			return
+		}
+		ok(c, gin.H{"deleted": true})
+	})
+}
+
+func setToolFavorite(c *gin.Context, svc *service.Service, favorite bool) {
+	user, err := currentUser(c, svc)
+	if err != nil {
+		failService(c, err)
+		return
+	}
+	toolID, err := parseToolID(c)
+	if err != nil {
+		fail(c, http.StatusBadRequest, err)
+		return
+	}
+	item, err := svc.SetToolFavorite(user.ID, toolID, favorite)
+	if err != nil {
+		failService(c, err)
+		return
+	}
+	ok(c, item)
+}
+
+func parseToolID(c *gin.Context) (int64, error) {
+	id, err := strconv.ParseInt(c.Param("id"), 10, 64)
+	if err != nil || id <= 0 {
+		return 0, errInvalidToolID
+	}
+	return id, nil
+}
+
+type toolIDError string
+
+func (e toolIDError) Error() string { return string(e) }
+
+const errInvalidToolID = toolIDError("工具 ID 无效")