feat: add Z12/Z13 bind APIs, stock import, and sync docs

Enable auto default sync channels on agent activate, bind-code/phone confirm flows, publish ALTER, and align admin/yuheng docs with the production bind path.

platform/internal/blueprint/merge.go

@@ -10,6 +10,7 @@ type MergeResult struct {
 	AddedPages       []string
 	AddedEntities    []string
 	AddedResources   []string
+	AddedFields      []string // entity.field
 	UpdatedPages     []string
 	UpdatedResources []string
 }
@@ -34,7 +35,13 @@ func MergeInto(base, incoming *Blueprint) (*MergeResult, error) {
 	}
 	for _, e := range incoming.Entities {
 		if idx, ok := entityByName[e.Name]; ok {
+			before := len(base.Entities[idx].Fields)
 			base.Entities[idx] = mergeEntity(base.Entities[idx], e)
+			if len(base.Entities[idx].Fields) > before {
+				for _, f := range base.Entities[idx].Fields[before:] {
+					res.AddedFields = append(res.AddedFields, e.Name+"."+f.Name)
+				}
+			}
 			continue
 		}
 		base.Entities = append(base.Entities, e)
@@ -105,6 +112,7 @@ func MergeInto(base, incoming *Blueprint) (*MergeResult, error) {
 	if len(res.AddedPages) == 0 &&
 		len(res.AddedEntities) == 0 &&
 		len(res.AddedResources) == 0 &&
+		len(res.AddedFields) == 0 &&
 		len(res.UpdatedPages) == 0 &&
 		len(res.UpdatedResources) == 0 {
 		return nil, fmt.Errorf("nothing new to publish: provide newly generated pages (and entities/apis if needed) for an existing app")