v1.1.5 of yjs_dart

A pure Dart translation of the Yjs CRDT library (yjs v14.0.0-22) and y-protocols (v1.0.5), with no external dependencies. Maintains a 1:1 structural mapping to the JavaScript source for easy diff-base [...] Changelog excerpt: - Resilience: readVarStringnow uses utf8.decode(..., allowMalformed: true)to tolerate invalid UTF-8 sequences (common in cross-platform CRDT string handling), preventing FormatExceptioncrashes. - Resilience: Observable.emitcatches and logs listener errors (e.g. signature mismatches) instead of crashing the app. This safeguards Docupdate propogation.