feat: complete i18n internationalization system with 9 language support

.github/workflows/ci.yml

@@ -20,6 +20,7 @@ jobs:
       - run: npx prettier --check .
       - run: npx eslint src/
       - run: npm run lint # TypeScript type checking
+      - run: npm run i18n:size-check # Translation bundle size budget
 
   test:
     runs-on: ubuntu-latest

.prettierignore

@@ -4,3 +4,4 @@ node_modules/
 coverage/
 *.min.js
 .gitignore
+.claude/

package.json

@@ -56,7 +56,10 @@
 		"test:integration:watch": "vitest --config vitest.integration.config.ts",
 		"test:performance": "vitest run --config vitest.performance.config.mts",
 		"refresh-speckit": "node scripts/refresh-speckit.mjs",
-		"refresh-openspec": "node scripts/refresh-openspec.mjs"
+		"refresh-openspec": "node scripts/refresh-openspec.mjs",
+		"i18n:audit": "npx tsx scripts/i18n-audit.ts",
+		"i18n:validate": "npx tsx scripts/i18n-validate.ts",
+		"i18n:size-check": "npx tsx scripts/i18n-size-check.ts"
 	},
 	"build": {
 		"npmRebuild": false,
@@ -240,13 +243,19 @@
 		"electron-store": "^8.1.0",
 		"electron-updater": "^6.6.2",
 		"fastify": "^4.25.2",
+		"i18next": "^25.8.17",
+		"i18next-browser-languagedetector": "^8.2.1",
+		"i18next-fs-backend": "^2.6.1",
+		"i18next-http-backend": "^3.0.2",
+		"i18next-resources-to-backend": "^1.2.1",
 		"js-tiktoken": "^1.0.21",
 		"marked": "^17.0.1",
 		"mermaid": "^11.12.1",
 		"node-pty": "^1.1.0",
 		"qrcode": "^1.5.4",
 		"qrcode.react": "^4.2.0",
 		"react-diff-view": "^3.3.2",
+		"react-i18next": "^16.5.6",
 		"react-markdown": "^10.1.0",
 		"react-syntax-highlighter": "^16.1.0",
 		"reactflow": "^11.11.4",
@@ -304,6 +313,7 @@
 		"react": "^18.2.0",
 		"react-dom": "^18.2.0",
 		"tailwindcss": "^3.4.1",
+		"tailwindcss-rtl": "^0.9.0",
 		"typescript": "^5.3.3",
 		"typescript-eslint": "^8.50.1",
 		"vite": "^5.0.11",
@@ -315,7 +325,7 @@
 	},
 	"lint-staged": {
 		"*": [
-			"prettier --write"
+			"prettier --write --ignore-unknown"
 		],
 		"*.{js,cjs,mjs,jsx,ts,tsx,mts,cts}": [
 			"eslint --fix"