docs(content): add issue URLs to problem pages and restructure guides into appendix

apps/docs/content/(03-hierarchical)/binary-search-tree/230-kth-smallest-element-in-a-bst.mdx

@@ -8,6 +8,7 @@ topics:
   - { name: "Binary Search Tree", slug: "binary-search-tree" }
   - { name: "Binary Tree", slug: "binary-tree" }
 video: "5LUXSvjmGCw"
+issue: "https://github.com/prdlk/leetcode/issues/112"
 sidebar:
   label: 'Kth Smallest Element in a BST'
   badge: 'Medium'

apps/docs/content/(03-hierarchical)/binary-search-tree/235-lowest-common-ancestor-of-a-binary-search-tree.mdx

@@ -10,6 +10,7 @@ topics:
   - { name: "Binary Lifting", slug: "binary-lifting" }
   - { name: "Lowest Common Ancestor", slug: "lowest-common-ancestor" }
 video: "gs2LMfuOR9k"
+issue: "https://github.com/prdlk/leetcode/issues/113"
 sidebar:
   label: 'Lowest Common Ancestor of a Binary Search Tree'
   badge: 'Medium'

apps/docs/content/(03-hierarchical)/binary-search-tree/98-validate-binary-search-tree.mdx

@@ -8,6 +8,7 @@ topics:
   - { name: "Binary Search Tree", slug: "binary-search-tree" }
   - { name: "Binary Tree", slug: "binary-tree" }
 video: "s6ATEkipzow"
+issue: "https://github.com/prdlk/leetcode/issues/111"
 sidebar:
   label: 'Validate Binary Search Tree'
   badge: 'Medium'

apps/docs/content/(03-hierarchical)/heap-priority-queue/215-kth-largest-element-in-an-array.mdx

@@ -9,6 +9,7 @@ topics:
   - { name: "Heap (Priority Queue)", slug: "heap-priority-queue" }
   - { name: "Quickselect", slug: "quickselect" }
 video: "XEmy13g1Qxc"
+issue: "https://github.com/prdlk/leetcode/issues/118"
 sidebar:
   label: 'Kth Largest Element in an Array'
   badge: 'Medium'

apps/docs/content/(03-hierarchical)/heap-priority-queue/23-merge-k-sorted-lists.mdx

@@ -9,6 +9,7 @@ topics:
   - { name: "Merge Sort", slug: "merge-sort" }
   - { name: "Tournament Sort", slug: "tournament-sort" }
 video: "q5a5OiGbT6Q"
+issue: "https://github.com/prdlk/leetcode/issues/120"
 sidebar:
   label: 'Merge k Sorted Lists'
   badge: 'Hard'

apps/docs/content/(03-hierarchical)/heap-priority-queue/973-k-closest-points-to-origin.mdx

@@ -12,6 +12,7 @@ topics:
   - { name: "Quickselect", slug: "quickselect" }
   - { name: "K-D Tree", slug: "k-d-tree" }
 video: "rI2EBUEMfTk"
+issue: "https://github.com/prdlk/leetcode/issues/119"
 sidebar:
   label: 'K Closest Points to Origin'
   badge: 'Medium'

apps/docs/content/(03-hierarchical)/tree-bfs/102-binary-tree-level-order-traversal.mdx

@@ -7,6 +7,7 @@ topics:
   - { name: "Breadth-First Search", slug: "breadth-first-search" }
   - { name: "Binary Tree", slug: "binary-tree" }
 video: "6ZnyEApgFYg"
+issue: "https://github.com/prdlk/leetcode/issues/106"
 sidebar:
   label: 'Binary Tree Level Order Traversal'
   badge: 'Medium'

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

@@ -8,6 +8,7 @@ topics:
   - { name: "Breadth-First Search", slug: "breadth-first-search" }
   - { name: "Binary Tree", slug: "binary-tree" }
 video: "7cp5imvDzl4"
+issue: "https://github.com/prdlk/leetcode/issues/108"
 sidebar:
   label: 'Count Good Nodes in Binary Tree'
   badge: 'Medium'

apps/docs/content/(03-hierarchical)/tree-bfs/199-binary-tree-right-side-view.mdx

@@ -8,6 +8,7 @@ topics:
   - { name: "Breadth-First Search", slug: "breadth-first-search" }
   - { name: "Binary Tree", slug: "binary-tree" }
 video: "d4zLyf32e3I"
+issue: "https://github.com/prdlk/leetcode/issues/107"
 sidebar:
   label: 'Binary Tree Right Side View'
   badge: 'Medium'

apps/docs/content/(03-hierarchical)/tree-dfs/104-maximum-depth-of-binary-tree.mdx

@@ -8,6 +8,7 @@ topics:
   - { name: "Breadth-First Search", slug: "breadth-first-search" }
   - { name: "Binary Tree", slug: "binary-tree" }
 video: "hTM3phVI6YQ"
+issue: "https://github.com/prdlk/leetcode/issues/97"
 sidebar:
   label: 'Maximum Depth of Binary Tree'
   badge: 'Easy'

apps/docs/content/(03-hierarchical)/tree-dfs/226-invert-binary-tree.mdx

@@ -8,6 +8,7 @@ topics:
   - { name: "Breadth-First Search", slug: "breadth-first-search" }
   - { name: "Binary Tree", slug: "binary-tree" }
 video: "OnSn2XEQ4MY"
+issue: "https://github.com/prdlk/leetcode/issues/96"
 sidebar:
   label: 'Invert Binary Tree'
   badge: 'Easy'

apps/docs/content/(03-hierarchical)/tree-dfs/236-lowest-common-ancestor-of-a-binary-tree.mdx

@@ -8,6 +8,7 @@ topics:
   - { name: "Binary Tree", slug: "binary-tree" }
   - { name: "Binary Lifting", slug: "binary-lifting" }
   - { name: "Lowest Common Ancestor", slug: "lowest-common-ancestor" }
+issue: "https://github.com/prdlk/leetcode/issues/98"
 sidebar:
   label: 'Lowest Common Ancestor of a Binary Tree'
   badge: 'Medium'

apps/docs/content/(03-hierarchical)/trie/208-implement-trie-prefix-tree.mdx

@@ -8,6 +8,7 @@ topics:
   - { name: "Design", slug: "design" }
   - { name: "Trie", slug: "trie" }
 video: "oobqoCJlHA0"
+issue: "https://github.com/prdlk/leetcode/issues/127"
 sidebar:
   label: 'Implement Trie (Prefix Tree)'
   badge: 'Medium'

apps/docs/content/(03-hierarchical)/trie/211-design-add-and-search-words-data-structure.mdx

@@ -8,6 +8,7 @@ topics:
   - { name: "Design", slug: "design" }
   - { name: "Trie", slug: "trie" }
 video: "BTf05gs_8iU"
+issue: "https://github.com/prdlk/leetcode/issues/128"
 sidebar:
   label: 'Design Add and Search Words Data Structure'
   badge: 'Medium'