fix(toc): align active heading strip with sidebar rail

The active indicator sat off the visual gutter and used rounding that
did not match the list. Square the strip and shift it to match the
rail so the focused row reads clearly without fighting the layout.

Made-with: Cursor

Author: HMarzban

packages/webapp/src/styles/components/_tableOfContents.scss

@@ -9,7 +9,7 @@
   content: '';
   position: absolute;
   top: 0;
-  left: 0.5px;
+  left: -8px;
   width: 4px;
   height: 100%;
   background-color: var(--color-docsy);
@@ -137,12 +137,12 @@
       left: -8px;
       top: 0;
       bottom: 0;
-      width: 3px;
+      width: 4px;
       background-color: var(--color-docsy);
       border-radius: 0;
       pointer-events: none;
       transition: left 0.2s ease-in-out;
-      border-radius: 10px;
+      border-radius: 4px;
     }
 
     &:hover::before {