fix(core): Migrate file I/O to @push.rocks/smartfs, adopt TC39 decorators v3 accessor in web components, and update docs/tests

ts_web/elements/letterheader.ts

@@ -31,25 +31,25 @@ export class DeLetterHeader extends DeesElement {
     type: Object,
     reflect: true,
   })
-  public letterData: plugins.tsclass.finance.TInvoice;
+  accessor letterData: plugins.tsclass.finance.TInvoice;
 
   @property({
     type: Number,
     reflect: true,
   })
-  public pageNumber: number = 1;
+  accessor pageNumber: number = 1;
 
   @property({
     type: Number,
     reflect: true,
   })
-  public pageTotalNumber: number = 1;
+  accessor pageTotalNumber: number = 1;
 
   @property({
     type: Object,
     reflect: true,
   })
-  public documentSettings: plugins.shared.interfaces.IDocumentSettings;
+  accessor documentSettings: plugins.shared.interfaces.IDocumentSettings;
 
   constructor() {
     super();