feat(FN-1457): fix stale subtask session title when minimizing newly started breakdown

- Refactor beginBreakdown() to accept explicit description parameter
- Update auto-start effect to pass current initialDescription directly
- Pass description as broadcastTitle to connectToSubtaskStream for correct background activity title
- Preserves existing send-to-background and cancel semantics

packages/dashboard/app/styles.css

@@ -8983,6 +8983,7 @@ body {
     justify-content: flex-end;
     border-top: 1px solid var(--border);
     padding: 0 4px;
+    min-height: 32px;
   }
 
   /* Hide text labels on action buttons to save space */
@@ -8994,15 +8995,15 @@ body {
   .terminal-restart-btn,
   .terminal-clear-btn {
     padding: 8px;
-    min-height: 36px;
-    min-width: 36px;
+    min-height: 32px;
+    min-width: 32px;
     justify-content: center;
   }
 
   .terminal-tab {
-    min-height: 48px;
-    padding: 12px 14px;
-    font-size: 14px;
+    min-height: 36px;
+    padding: 6px 10px;
+    font-size: 13px;
   }
 
   .terminal-tab-label {
@@ -9010,8 +9011,8 @@ body {
   }
 
   .terminal-close {
-    width: 48px;
-    height: 48px;
+    width: 36px;
+    height: 36px;
   }
 
   .terminal-toolbar {