docs(docs): add ProblemBadges component, layout slot, and enrich pages with topics/video frontmatter, plus guide placeholders and topic‑landing map.

apps/docs/content/(03-hierarchical)/tree-bfs/1448-count-good-nodes-in-binary-tree.mdx

@@ -2,13 +2,17 @@
 title: '1448. Count Good Nodes in Binary Tree'
 description: Given a binary tree root, a node X in the tree is named good if in the path from root to X there are no nodes with a value greater than X
 icon: dot
+topics:
+  - { name: "Tree", slug: "tree" }
+  - { name: "Depth-First Search", slug: "depth-first-search" }
+  - { name: "Breadth-First Search", slug: "breadth-first-search" }
+  - { name: "Binary Tree", slug: "binary-tree" }
+video: "7cp5imvDzl4"
 sidebar:
   label: 'Count Good Nodes in Binary Tree'
   badge: 'Medium'
 ---
 
-<Badge variant="accent">Tree</Badge>
-
 ### Example 1:
 - Input: `root = [3,1,4,3,null,1,5]`
 - Output: `4`
@@ -67,7 +71,3 @@ class Solution:
 
         return dfs(root, root.val)
 ```
-
-## Explanation
-
-<YouTube id="7cp5imvDzl4" title="Microsoft's Most Asked Question 2021 - Count Good Nodes in a Binary Tree - Leetcode 1448 - Python" />