feat(auth): enhance watcher with asynchronous dispatch and buffering

- Added async dispatch loop to `Watcher` for handling incremental `AuthUpdate` with in-memory buffering.
- Improved resilience against high-frequency auth changes by coalescing updates and reducing redundant processing.
- Updated `cliproxy` service to increase auth update queue capacity and optimize backlog consumption.
- Added detailed SDK integration documentation in English and Chinese (`sdk-watcher.md`, `sdk-watcher_CN.md`).

sdk/cliproxy/service.go

@@ -78,7 +78,7 @@ func (s *Service) ensureAuthUpdateQueue(ctx context.Context) {
 		return
 	}
 	if s.authUpdates == nil {
-		s.authUpdates = make(chan watcher.AuthUpdate, 64)
+		s.authUpdates = make(chan watcher.AuthUpdate, 256)
 	}
 	if s.authQueueStop != nil {
 		return
@@ -98,6 +98,14 @@ func (s *Service) consumeAuthUpdates(ctx context.Context) {
 				return
 			}
 			s.handleAuthUpdate(ctx, update)
+			for {
+				select {
+				case nextUpdate := <-s.authUpdates:
+					s.handleAuthUpdate(ctx, nextUpdate)
+				default:
+					break
+				}
+			}
 		}
 	}
 }