docs(docs): add Reorder List page, rename phase titles, update redirects

apps/docs/content/(02-nodal-grid)/linked-list/143_reorder-list.mdx

@@ -0,0 +1,42 @@
+---
+title: '143. Reorder List'
+description: 'You are given the head of a singly linked-list. The list can be represented as:'
+icon: dot
+topics:
+  - { name: "Linked List", slug: "linked-list" }
+  - { name: "Two Pointers", slug: "two-pointers" }
+  - { name: "Stack", slug: "stack" }
+  - { name: "Recursion", slug: "recursion" }
+issue: "https://github.com/prdlk/leetcode/issues/81"
+sidebar:
+  label: 'Reorder List'
+  badge: 'Medium'
+---
+
+### Example 1:
+- Input: `head = [1,2,3,4]`
+- Output: `[1,4,2,3]`
+
+### Example 2:
+- Input: `head = [1,2,3,4,5]`
+- Output: `[1,5,2,4,3]`
+
+### Constraints:
+
+- The number of nodes in the list is in the range [1, 5 * 10^4].
+- `1 <= Node.val <= 1000`
+
+## Solution
+
+```py
+# Definition for singly-linked list.
+# class ListNode:
+#     def __init__(self, val=0, next=None):
+#         self.val = val
+#         self.next = next
+class Solution:
+    def reorderList(self, head: ListNode | None) -> None:
+        """
+        Do not return anything, modify head in-place instead.
+        """
+```