Enhance tooltip functionality for CPU standard deviation in dashboard

- Updated the tooltip for the CPU standard deviation metric to include a detailed explanation of the calculation, preserving newlines for better readability.
- Added CSS styles to support multi-line tooltips, improving user comprehension of the displayed data.

static/css/main.css

@@ -340,4 +340,10 @@ label.swap:focus-within:not(.theme-toggle) {
   .print-only {
     display: none !important;
   }
+}
+
+/* Multi-line tooltip (formula): preserve newlines from data-tip */
+.tooltip-formula[data-tip]::before {
+  white-space: pre-line;
+  text-align: left;
 }

templates/dashboard/_chart_migrations.html

@@ -13,7 +13,7 @@
                 </div>
                 <div id="currentCpuStdBlock" class="flex items-center gap-1 text-xs">
                     <div class="w-3 h-0.5 bg-error/60"></div>
-                    <span class="tooltip tooltip-top text-error/60 cursor-help" data-tip="σ = √(Σ(xᵢ−μ)²/n)" aria-label="Формула расчёта ±0.5σ">
+                    <span class="tooltip tooltip-top tooltip-formula text-error/60 cursor-help" data-tip="Показывает разброс утилизации CPU относительно среднего.&#10;&#10;μ — средняя утилизация CPU по хостам.&#10;σ — стандартное отклонение:&#10;σ = √(Σ(xᵢ−μ)²/n)." aria-label="Формула расчёта ±0.5σ">
                         <span class="text-error/60">±0.5σ: <span id="currentCpuStd">0</span>%</span>
                     </span>
                 </div>