feat: add schema fingerprint and Z10d alter; refresh sync coop docs

Ship ensure ADD COLUMN and fingerprint API for Yuheng reconcile, and rewrite §0.2–0.3 cooperation checklist in the联调意见.

Co-authored-by: Cursor <cursoragent@cursor.com>

platform/internal/handler/agent_sync.go

@@ -403,6 +403,53 @@ func agentSyncSchemaDescribeHandler(svcCtx *svc.ServiceContext) http.HandlerFunc
 	}
 }
 
+func agentSyncSchemaFingerprintHandler(svcCtx *svc.ServiceContext) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		started := time.Now()
+		reqID := r.Header.Get("X-Request-Id")
+		if !requireDBSync(svcCtx, w) {
+			return
+		}
+		channelID := pathvar.Vars(r)["id"]
+		ch, err := svcCtx.DBSync.Store().GetChannelForTenant(channelID, syncTenantID(r))
+		if err != nil {
+			authx.WriteError(w, http.StatusNotFound, err.Error())
+			return
+		}
+		var req dbsync.FingerprintRequest
+		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+			authx.WriteError(w, http.StatusBadRequest, err.Error())
+			return
+		}
+		if !authorizeUserOnlineDB(svcCtx, w, r, channelID, req.OnlineDBID, "用户自助 schema/fingerprint 须带 online_db_id，且须为本人 Binding") {
+			return
+		}
+		if !authorizeUserSyncChannel(svcCtx, w, r, channelID) {
+			return
+		}
+		res, err := dbsync.FingerprintRemoteTables(r.Context(), ch, req)
+		dur := time.Since(started)
+		if err != nil {
+			logSyncReq(r, "schema/fingerprint", channelID, "", "", "err", err.Error(), dur, reqID)
+			if dbsync.IsRetryable(err) {
+				authx.WriteRetryableError(w, http.StatusServiceUnavailable, err.Error())
+				return
+			}
+			authx.WriteError(w, http.StatusBadRequest, err.Error())
+			return
+		}
+		n := 0
+		if res != nil {
+			n = len(res.Tables)
+		}
+		logSyncReq(r, "schema/fingerprint", channelID, "", "", "ok", "", dur, reqID)
+		auditSync(svcCtx, r, "dbsync.schema_fingerprint", map[string]any{
+			"channel_id": channelID, "n": n, "ms": dur.Milliseconds(), "req_id": reqID,
+		})
+		httpx.OkJson(w, map[string]any{"success": true, "result": res})
+	}
+}
+
 func uniqueStringSlice(a, b []string) []string {
 	seen := map[string]struct{}{}
 	var out []string