docs: add companies frontmatter, schema, and rendering in badges & appendix pages

apps/docs/content/(01-linear-structures)/monotonic-stack/853_car-fleet.mdx

@@ -9,6 +9,9 @@ topics:
   - { name: "Monotonic Stack", slug: "monotonic-stack" }
 video: "Pr6T-3yB9RM"
 issue: "https://github.com/prdlk/leetcode/issues/73"
+companies:
+  - { name: "Google", period: "Three Months", frequency: 17.3 }
+  - { name: "Amazon", period: "Six Months", frequency: 26 }
 sidebar:
   label: 'Car Fleet'
   badge: 'Medium'