fix(maestro): pin activity rail to left edge, drop active-state pulse

Rail now spans full row height flush to the left edge with square
corners, instead of a depth-shifted inset bar. Active state stays
solid green since colour alone already signals it; blink/flash stay
for awaiting-input/error.

web/src/catalog.ts

@@ -68,13 +68,11 @@ const STATE_WORDS: Record<string, string> = {
   error: "Error",
 };
 
-/** docs/SIDEBAR.md: the activity rail sits inside the row's own indent
- * gutter, so it shifts outward with nesting depth exactly as that gutter
- * does. `depth * 16 + 8` is the same expression `renderNode` uses for the
- * row's own padding — the rail sits just inside it. */
-function activityRailMarkup(slug: string, stateWord: string, depth: number): string {
-  const left = depth * 16 + 2;
-  return `<span class="activity-rail" data-activity="${slug}" style="left:${left}px" role="img" title="${escapeHtml(stateWord)}" aria-label="${escapeHtml(stateWord)}"></span>`;
+/** docs/SIDEBAR.md: the activity rail is pinned to the row's own left edge,
+ * full height. The row's own padding (`renderNode`) shifts outward with
+ * nesting depth, carrying the rail with it. */
+function activityRailMarkup(slug: string, stateWord: string): string {
+  return `<span class="activity-rail" data-activity="${slug}" role="img" title="${escapeHtml(stateWord)}" aria-label="${escapeHtml(stateWord)}"></span>`;
 }
 
 function metaLine(s: Session, now: number): string {
@@ -172,7 +170,7 @@ function renderNode(node: TreeNode, depth: number): HTMLElement {
   );
   // docs/SIDEBAR.md: line 1 reserves action width, and line 2 is unconditional.
   row.innerHTML = `
-    ${activityRailMarkup(slug, stateWord, depth)}
+    ${activityRailMarkup(slug, stateWord)}
     <span class="card-line1">
       <span class="leaf-name">${escapeHtml(name)}</span>
       <span class="leaf-actions">