feat: portfolio redesign with i18n, RBC project showcase, CI/CD

- Add i18n support (EN/ZH) with language toggle
- Redesign header with education dropdown, contact copy buttons
- Add RBC project showcase with bullet points, skills highlighting
- Create terraform-drift placeholder page
- Add ProjectShowcase component with media toggle (image/video)
- Update experience timeline with action-driven descriptions
- Add Docker + Forgejo CI workflow for image builds
- Update K8s manifests for riotpiao.com ingress
- Add DESIGN.md documenting design system patterns

lib/LanguageContext.tsx

@@ -0,0 +1,34 @@
+'use client'
+
+import { createContext, useContext, useState, ReactNode } from 'react'
+import translations from './translations.json'
+
+type Language = 'en' | 'zh'
+
+interface LanguageContextType {
+  lang: Language
+  setLang: (lang: Language) => void
+  t: typeof translations.en
+}
+
+const LanguageContext = createContext<LanguageContextType | undefined>(undefined)
+
+export function LanguageProvider({ children }: { children: ReactNode }) {
+  const [lang, setLang] = useState<Language>('en')
+
+  const t = lang === 'zh' ? translations.zh : translations.en
+
+  return (
+    <LanguageContext.Provider value={{ lang, setLang, t }}>
+      {children}
+    </LanguageContext.Provider>
+  )
+}
+
+export function useLanguage() {
+  const context = useContext(LanguageContext)
+  if (!context) {
+    throw new Error('useLanguage must be used within LanguageProvider')
+  }
+  return context
+}