feat: add Kbd component and blog post about IDEA schema validation bug

Add a Kbd component with macOS special key support (⌘, ⌥, ⌃, ⇧, etc.),
export it from theme/index.tsx for use in MDX files.

Add blog posts (EN + ZH) documenting the IntelliJ IDEA application.yaml
schema validation bug caused by an overly broad fileMatch pattern in
SchemaStore, along with the quick fix.

theme/components/Kbd.tsx

@@ -0,0 +1,60 @@
+import type { HTMLAttributes } from "react"
+
+const macOSSymbols: Record<string, string> = {
+  cmd: "⌘",
+  command: "⌘",
+  opt: "⌥",
+  option: "⌥",
+  alt: "⌥",
+  ctrl: "⌃",
+  control: "⌃",
+  shift: "⇧",
+  enter: "↩",
+  return: "↩",
+  tab: "⇥",
+  esc: "⎋",
+  escape: "⎋",
+  delete: "⌫",
+  backspace: "⌫",
+  forwardDelete: "⌦",
+  up: "↑",
+  down: "↓",
+  left: "←",
+  right: "→",
+  space: "␣",
+  fn: "Fn",
+  globe: "🌐",
+  eject: "⏏",
+  power: "⏻",
+  capslock: "⇪",
+  home: "↖",
+  end: "↘",
+  pageup: "⇞",
+  pagedown: "⇟",
+  clear: "⌧",
+}
+
+export interface KbdProps extends HTMLAttributes<HTMLElement> {
+  mac?: keyof typeof macOSSymbols
+}
+
+export function Kbd({ children, mac, className = "", ...rest }: KbdProps) {
+  const label = children ?? (mac ? macOSSymbols[mac] : null)
+  if (!label) return null
+
+  return (
+    <kbd
+      className={`inline-flex items-center justify-center min-w-[1.6em] px-1.5 py-0
+        text-[0.85em] leading-normal font-mono
+        rounded-md border border-b-2
+        border-gray-300 dark:border-gray-600
+        bg-gray-50 dark:bg-gray-800
+        text-gray-700 dark:text-gray-300
+        shadow-[0_1px_1px_rgba(0,0,0,0.075)]
+        align-baseline
+        ${className}`.replace(/\s+/g, " ")}
+      {...rest}>
+      {label}
+    </kbd>
+  )
+}