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)/prefix-sum/303-range-sum-query-immutable.mdx

@@ -2,13 +2,16 @@
 title: '303. Range Sum Query - Immutable'
 description: Given an integer array nums, handle multiple queries of the following type
 icon: dot
+topics:
+  - { name: "Array", slug: "array" }
+  - { name: "Design", slug: "design" }
+  - { name: "Prefix Sum", slug: "prefix-sum" }
+video: "2pndAmo_sMA"
 sidebar:
   label: 'Range Sum Query - Immutable'
   badge: 'Easy'
 ---
 
-<Badge variant="accent">Array</Badge>
-
 ### Example 1:
 - Input: `["NumArray", "sumRange", "sumRange", "sumRange"]` `[[[-2, 0, 3, -5, 2, -1]], [0, 2], [2, 5], [0, 5]]`
 - Output: `[null, 1, -1, -3]`
@@ -66,7 +69,3 @@ class NumArray {
  * var param_1 = obj.sumRange(left,right)
  */
 ```
-
-## Explanation
-
-<YouTube id="2pndAmo_sMA" title="Range Sum Query Immutable - Leetcode 303 - Python" />