feat: Integrate JS Gantt Chart library and update styles

- Added JS Gantt Chart library files including CSS and JS.
- Updated existing Gantt chart styles for better visual representation.
- Translated month and day names to Polish in the Gantt chart settings.
- Implemented Gantt chart initialization in the main view with sample data.
- Added a toggle switch for displaying tasks in the calendar.
- Enhanced task edit form with a new checkbox for calendar visibility.
- Improved the layout of the logged-in user template to include Gantt chart styles and scripts.

libraries/jquery-gantt/jquery-gantt.css

@@ -55,7 +55,7 @@
   display: inline-block;
   margin: 0 0 0 5px;
   color: #484A4D;
-  width: 110px;
+  width: 100%;
   white-space: nowrap;
   text-overflow: ellipsis;
   overflow: hidden;
@@ -204,17 +204,36 @@
   border-radius: 3px;
 }
 
+.fn-gantt .bar.ganttGrey {
+  background-color: #f0f0f0;
+  -webkit-box-shadow: 0 0 1px rgba(0, 0, 0, 0.25) inset;
+  -moz-box-shadow: 0 0 1px rgba(0, 0, 0, 0.25) inset;
+  box-shadow: 0 0 1px rgba(0, 0, 0, 0.25) inset;
+}
+
+/* ganttRed */
+.fn-gantt .bar.ganttRed {
+  background-color: #772626;
+  -webkit-box-shadow: 0 0 1px rgba(0, 0, 0, 0.25) inset;
+  -moz-box-shadow: 0 0 1px rgba(0, 0, 0, 0.25) inset;
+  box-shadow: 0 0 1px rgba(0, 0, 0, 0.25) inset;
+}
+
 .fn-gantt .bar .fn-label {
   line-height: 18px;
-  font-weight: bold;
+  font-weight: 400;
   white-space: nowrap;
   width: 100%;
-  color: #414B57 !important;
+  color: #414B57;
   text-align: center;
   font-size: 11px;
   text-indent: 5px;
 }
 
+.fn-content .bar.ganttRed .fn-label {
+  color: #FFF;
+}
+
 .fn-gantt .gantt10 {
   background-color: #cc0000;
 }