refactor(msg_gateway): decouple bot gateway and push notification architecture

- Split shared monolithic consts into bot, push, and errs with typed sentinel errors
- Restructure model layer into distinct bot and push subdomains
- Refactor DAO layer to enforce single-owner principle and remove cross-table raw SQL queries
- Decompose 1150+ line service/push.go into push_channel, push_event, push_trigger, push_worker, and push_template
- Clean up controller layer with generic request handlers and parameter validation in controller/base.go
- Streamline plugin.go to core Cordis lifecycle orchestration and remove re-export bloat
- Verify all unit tests, race tests, Cordis architecture rules, and Swagger generation pass cleanly

backend/plugins/domain/msg_gateway/controller/base.go

@@ -0,0 +1,69 @@
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
+package controller
+
+import (
+	"Wavelet/core/contracts"
+	"Wavelet/pkg/ginutil"
+	"Wavelet/pkg/response"
+	"context"
+	"net/http"
+	"strconv"
+
+	"github.com/gin-gonic/gin"
+)
+
+// currentUser extracts the authenticated UserDTO from gin.Context.
+func currentUser(c *gin.Context) (*contracts.UserDTO, bool) {
+	return ginutil.GetFromContext[*contracts.UserDTO](c, contracts.AuthUserObjKey)
+}
+
+// parseUint64Param parses a uint64 URL path parameter.
+func parseUint64Param(c *gin.Context, paramName, errInvalid string) (uint64, bool) {
+	id, err := strconv.ParseUint(c.Param(paramName), 10, 64)
+	if err != nil {
+		response.AbortBadRequest(c, errInvalid)
+		return 0, false
+	}
+	return id, true
+}
+
+// handleJSONRequest binds a JSON body, executes the service handler, and writes the standard success envelope.
+func handleJSONRequest[Req any, Res any](c *gin.Context, handler func(ctx context.Context, req Req) (Res, error)) {
+	var req Req
+	if err := c.ShouldBindJSON(&req); err != nil {
+		response.AbortBadRequest(c, err.Error())
+		return
+	}
+	res, err := handler(c.Request.Context(), req)
+	if err != nil {
+		response.AbortBadRequest(c, err.Error())
+		return
+	}
+	c.JSON(http.StatusOK, response.OK(res))
+}
+
+// handleEntityUpdate resolves a path identifier and JSON body, executes the updater, and handles errors with onErr.
+func handleEntityUpdate[Req any, Res any](
+	c *gin.Context,
+	parseID func(*gin.Context) (uint64, bool),
+	updater func(ctx context.Context, id uint64, req Req) (Res, error),
+	onErr func(*gin.Context, error),
+) {
+	id, ok := parseID(c)
+	if !ok {
+		return
+	}
+	var req Req
+	if err := c.ShouldBindJSON(&req); err != nil {
+		response.AbortBadRequest(c, err.Error())
+		return
+	}
+	dto, err := updater(c.Request.Context(), id, req)
+	if err != nil {
+		onErr(c, err)
+		return
+	}
+	c.JSON(http.StatusOK, response.OK(dto))
+}