fix: add fixed min-width to sidebar panels to prevent content clipping (#7212)

## Summary

The default 10% min-size is too small for panels like Media Assets,
causing content to be clipped.
Use a fixed minimum width to ensure the panel content displays properly.

fix https://github.com/Comfy-Org/ComfyUI_frontend/issues/7210

## Screenshots


https://github.com/user-attachments/assets/65a15f0f-45c1-4361-adc9-eee4ccfad0ee

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-7212-fix-add-fixed-min-width-to-sidebar-panels-to-prevent-content-clipping-2c16d73d365081d8a5a4de30c8eb5e07)
by [Unito](https://www.unito.io)

src/components/LiteGraphCanvasSplitterOverlay.vue

@@ -24,7 +24,12 @@
       >
         <SplitterPanel
           v-if="sidebarLocation === 'left' && !focusMode"
-          class="side-bar-panel bg-comfy-menu-bg pointer-events-auto"
+          :class="
+            cn(
+              'side-bar-panel bg-comfy-menu-bg pointer-events-auto',
+              sidebarPanelVisible && 'min-w-78'
+            )
+          "
           :min-size="10"
           :size="20"
           :style="{
@@ -70,7 +75,12 @@
 
         <SplitterPanel
           v-if="sidebarLocation === 'right' && !focusMode"
-          class="side-bar-panel pointer-events-auto"
+          :class="
+            cn(
+              'side-bar-panel pointer-events-auto',
+              sidebarPanelVisible && 'min-w-78'
+            )
+          "
           :min-size="10"
           :size="20"
           :style="{