Adopt shared WebUI structural primitives

webui/src/styles/scheduling.css

@@ -1,12 +1,3 @@
-.scheduling-page {
-  box-sizing: border-box;
-  height: calc(100vh - 115px);
-  min-height: 0;
-  overflow: hidden;
-  color: var(--text);
-  background: var(--bg);
-}
-
 .scheduling-public-page {
   width: min(920px, calc(100% - 32px));
   margin: 0 auto;
@@ -107,12 +98,6 @@
   }
 }
 
-.scheduling-page *,
-.scheduling-page *::before,
-.scheduling-page *::after {
-  box-sizing: border-box;
-}
-
 .scheduling-workspace {
   width: 100%;
   height: 100%;
@@ -337,12 +322,6 @@
   justify-items: start;
 }
 
-.scheduling-columns {
-  display: grid;
-  grid-template-columns: repeat(2, minmax(0, 1fr));
-  gap: 12px;
-}
-
 .scheduling-compact-row {
   min-height: 36px;
   display: grid;
@@ -459,10 +438,6 @@
     border-bottom: var(--border-line);
   }
 
-  .scheduling-columns {
-    grid-template-columns: minmax(0, 1fr);
-  }
-
   .scheduling-page-header {
     align-items: flex-start;
     flex-wrap: wrap;