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)/sliding-window/121-best-time-to-buy-and-sell-stock.mdx

@@ -2,13 +2,15 @@
 title: '121. Best Time to Buy and Sell Stock'
 description: You are given an array prices where prices[i] is the price of a given stock on the i^th day
 icon: dot
+topics:
+  - { name: "Array", slug: "array" }
+  - { name: "Dynamic Programming", slug: "dynamic-programming" }
+video: "1pkOgXD63yU"
 sidebar:
   label: 'Best Time to Buy and Sell Stock'
   badge: 'Easy'
 ---
 
-<Badge variant="accent">Array</Badge>
-
 ### Example 1:
 - Input: `prices = [7,1,5,3,6,4]`
 - Output: `5`
@@ -55,7 +57,3 @@ class Solution:
             ans = max(ans, curr)
         return ans
 ```
-
-## Explanation
-
-<YouTube id="1pkOgXD63yU" title="Sliding Window: Best Time to Buy and Sell Stock - Leetcode 121 - Python" />

apps/docs/content/(01-linear-structures)/sliding-window/3-longest-substring-without-repeating-characters.mdx

@@ -2,13 +2,16 @@
 title: '3. Longest Substring Without Repeating Characters'
 description: Given a string s, find the length of the longest substring without duplicate characters
 icon: dot
+topics:
+  - { name: "Hash Table", slug: "hash-table" }
+  - { name: "String", slug: "string" }
+  - { name: "Sliding Window", slug: "sliding-window" }
+video: "wiGpQwVHdE0"
 sidebar:
   label: 'Longest Substring Without Repeating Characters'
   badge: 'Medium'
 ---
 
-<Badge variant="accent">Hash Table</Badge>
-
 ### Example 1:
 - Input: `s = "abcabcbb"`
 - Output: `3`
@@ -61,7 +64,3 @@ class Solution:
 
         return ans
 ```
-
-## Explanation
-
-<YouTube id="wiGpQwVHdE0" title="Longest Substring Without Repeating Characters - Leetcode 3 - Python" />

apps/docs/content/(01-linear-structures)/sliding-window/424-longest-repeating-character-replacement.mdx

@@ -2,13 +2,16 @@
 title: '424. Longest Repeating Character Replacement'
 description: You are given a string s and an integer k. You can choose any character of the string and change it to any other uppercase English character. You can perform this operation at most k times
 icon: dot
+topics:
+  - { name: "Hash Table", slug: "hash-table" }
+  - { name: "String", slug: "string" }
+  - { name: "Sliding Window", slug: "sliding-window" }
+video: "gqXU1UyA8pk"
 sidebar:
   label: 'Longest Repeating Character Replacement'
   badge: 'Medium'
 ---
 
-<Badge variant="accent">Hash Table</Badge>
-
 ### Example 1:
 - Input: `s = "ABAB", k = 2`
 - Output: `4`
@@ -61,7 +64,3 @@ class Solution:
             res = max(res, r - l + 1)
         return res
 ```
-
-## Explanation
-
-<YouTube id="gqXU1UyA8pk" title="Longest Repeating Character Replacement - Leetcode 424 - Python" />

apps/docs/content/(01-linear-structures)/sliding-window/567-permutation-in-string.mdx

@@ -2,13 +2,17 @@
 title: '567. Permutation in String'
 description: Given two strings s1 and s2, return true if s2 contains a permutation of s1, or false otherwise
 icon: dot
+topics:
+  - { name: "Hash Table", slug: "hash-table" }
+  - { name: "Two Pointers", slug: "two-pointers" }
+  - { name: "String", slug: "string" }
+  - { name: "Sliding Window", slug: "sliding-window" }
+video: "UbyhOgBN834"
 sidebar:
   label: 'Permutation in String'
   badge: 'Medium'
 ---
 
-<Badge variant="accent">Hash Table</Badge>
-
 ### Example 1:
 - Input: `s1 = "ab", s2 = "eidbaooo"`
 - Output: `true`
@@ -68,7 +72,3 @@ class Solution:
 
         return False
 ```
-
-## Explanation
-
-<YouTube id="UbyhOgBN834" title="Permutation in String - Leetcode 567 - Python" />