feat: introduce OverlayContext for managing application overlay states

Author: sametuca

src/context/OverlayContext.tsx

@@ -1,4 +1,5 @@
-import { createContext, useContext, useState, type ReactNode } from 'react'
+import { createContext, useContext, useState } from 'react'
+import type { ReactNode } from 'react'
 
 type OverlayType = 'none' | 'projects' | 'cv' | 'contact' | 'terminal' | 'certificates'