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

apps/docs/content/(01-linear-structures)/hash-table/217-contains-duplicate.mdx

@@ -2,13 +2,16 @@
 title: '217. Contains Duplicate'
 description: Given an integer array nums, return true if any value appears at least twice in the array, and return false if every element is distinct
 icon: dot
+topics:
+  - { name: "Array", slug: "array" }
+  - { name: "Hash Table", slug: "hash-table" }
+  - { name: "Sorting", slug: "sorting" }
+video: "3OamzN90kPg"
 sidebar:
   label: 'Contains Duplicate'
   badge: 'Easy'
 ---
 
-<Badge variant="accent">Array</Badge>
-
 ### Example 1:
 - Input: `nums = [1,2,3,1]`
 - Output: `true`
@@ -48,7 +51,3 @@ class Solution:
     def containsDuplicate(self, nums: List[int]) -> bool:
         return len(set(nums)) != len(nums)
 ```
-
-## Explanation
-
-<YouTube id="3OamzN90kPg" title="Contains Duplicate - Leetcode 217 - Python" />