Update dashboard metrics and enhance CPU statistics visualization

- Expanded mock data to include additional host labels and updated CPU current and projected values for better representation.
- Modified JavaScript to conditionally display projected CPU statistics and standard deviation, improving user experience.
- Refactored chart configuration to dynamically handle datasets based on the presence of projected data.
- Updated HTML to include a new block for displaying standard deviation, enhancing clarity in CPU metrics presentation.

templates/dashboard/_chart_migrations.html

@@ -11,7 +11,7 @@
                     <div class="w-3 h-0.5 bg-success"></div>
                     <span class="text-success">Mean: <span id="currentCpuMean">0</span>%</span>
                 </div>
-                <div class="flex items-center gap-1 text-xs">
+                <div id="currentCpuStdBlock" class="flex items-center gap-1 text-xs">
                     <div class="w-3 h-0.5 bg-error/60"></div>
                     <span class="text-error/60">±0.5σ: <span id="currentCpuStd">0</span>%</span>
                 </div>