fix(i18n): add axios dependency and fix DeepL API parameters

- Install axios for DeepL HTTP requests
- Remove unsupported preserve_formatting parameter from DeepL API calls
- Add formality parameter only for supported languages (DE, FR, etc.)
- Tested successfully: 'Hello, World!' → 'Hallo, Welt!'

DeepL API Status:
- API key configured (free tier: 500k chars/month)
- Current usage: 12,131 / 500,000 characters (2.43%)
- Remaining quota: 487,869 characters

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

package-lock.json

@@ -9,6 +9,7 @@
       "version": "0.1.0",
       "license": "Apache-2.0",
       "dependencies": {
+        "axios": "^1.12.2",
         "bcrypt": "^5.1.1",
         "cookie-parser": "^1.4.7",
         "cors": "^2.8.5",
@@ -1830,7 +1831,6 @@
       "version": "0.4.0",
       "resolved": "https://registry.npmjs.org/asynckit/-/asynckit-0.4.0.tgz",
       "integrity": "sha512-Oei9OH4tRh0YqU3GxhX79dM/mwVgvbZJaSNaRk+bshkj0S5cfHcgYakreBjrHwatXKbz+IoIdYLxrKim2MjW0Q==",
-      "dev": true,
       "license": "MIT"
     },
     "node_modules/autoprefixer": {
@@ -1881,6 +1881,17 @@
         "node": ">=4"
       }
     },
+    "node_modules/axios": {
+      "version": "1.12.2",
+      "resolved": "https://registry.npmjs.org/axios/-/axios-1.12.2.tgz",
+      "integrity": "sha512-vMJzPewAlRyOgxV2dU0Cuz2O8zzzx9VYtbJOaBgXFeLc4IV/Eg50n4LowmehOOR61S8ZMpc2K5Sa7g6A4jfkUw==",
+      "license": "MIT",
+      "dependencies": {
+        "follow-redirects": "^1.15.6",
+        "form-data": "^4.0.4",
+        "proxy-from-env": "^1.1.0"
+      }
+    },
     "node_modules/b4a": {
       "version": "1.7.3",
       "resolved": "https://registry.npmjs.org/b4a/-/b4a-1.7.3.tgz",
@@ -2651,7 +2662,6 @@
       "version": "1.0.8",
       "resolved": "https://registry.npmjs.org/combined-stream/-/combined-stream-1.0.8.tgz",
       "integrity": "sha512-FQN4MRfuJeHf7cBbBMJFXhKSDq+2kAArBlmRBvcvFE5BB1HZKXtSFASDhdlz9zOYwxh8lDdnvmMOe/+5cdoEdg==",
-      "dev": true,
       "license": "MIT",
       "dependencies": {
         "delayed-stream": "~1.0.0"
@@ -3081,7 +3091,6 @@
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/delayed-stream/-/delayed-stream-1.0.0.tgz",
       "integrity": "sha512-ZySD7Nf91aLB0RxL4KGrKHBXl7Eds1DAmEdcoVawXnLD7SDhpNgtuII2aAkg7a7QS41jxPSZ17p4VdGnMHk3MQ==",
-      "dev": true,
       "license": "MIT",
       "engines": {
         "node": ">=0.4.0"
@@ -3415,7 +3424,6 @@
       "version": "2.1.0",
       "resolved": "https://registry.npmjs.org/es-set-tostringtag/-/es-set-tostringtag-2.1.0.tgz",
       "integrity": "sha512-j6vWzfrGVfyXxge+O0x5sh6cvxAog0a/4Rdd2K36zCMV5eJ+/+tOAngRO8cODMNWbVRdVlmGZQL2YS3yR8bIUA==",
-      "dev": true,
       "license": "MIT",
       "dependencies": {
         "es-errors": "^1.3.0",
@@ -4019,6 +4027,26 @@
       "integrity": "sha512-GRnmB5gPyJpAhTQdSZTSp9uaPSvl09KoYcMQtsB9rQoOmzs9dH6ffeccH+Z+cv6P68Hu5bC6JjRh4Ah/mHSNRw==",
       "license": "MIT"
     },
+    "node_modules/follow-redirects": {
+      "version": "1.15.11",
+      "resolved": "https://registry.npmjs.org/follow-redirects/-/follow-redirects-1.15.11.tgz",
+      "integrity": "sha512-deG2P0JfjrTxl50XGCDyfI97ZGVCxIpfKYmfyrQ54n5FO/0gfIES8C/Psl6kWVDolizcaaxZJnTS0QSMxvnsBQ==",
+      "funding": [
+        {
+          "type": "individual",
+          "url": "https://github.com/sponsors/RubenVerborgh"
+        }
+      ],
+      "license": "MIT",
+      "engines": {
+        "node": ">=4.0"
+      },
+      "peerDependenciesMeta": {
+        "debug": {
+          "optional": true
+        }
+      }
+    },
     "node_modules/foreground-child": {
       "version": "3.3.1",
       "resolved": "https://registry.npmjs.org/foreground-child/-/foreground-child-3.3.1.tgz",
@@ -4053,7 +4081,6 @@
       "version": "4.0.4",
       "resolved": "https://registry.npmjs.org/form-data/-/form-data-4.0.4.tgz",
       "integrity": "sha512-KrGhL9Q4zjj0kiUt5OO4Mr/A/jlI2jDYs5eHBpYHPcBEVSiipAvn2Ko2HnPe20rmcuuvMHNdZFp+4IlGTMF0Ow==",
-      "dev": true,
       "license": "MIT",
       "dependencies": {
         "asynckit": "^0.4.0",
@@ -4390,7 +4417,6 @@
       "version": "1.0.2",
       "resolved": "https://registry.npmjs.org/has-tostringtag/-/has-tostringtag-1.0.2.tgz",
       "integrity": "sha512-NqADB8VjPFLM2V0VvHUewwwsw0ZWBaIdgo+ieHtK3hasLz4qeCRjYcqfB6AQrBggRKppKF8L52/VqdVsO47Dlw==",
-      "dev": true,
       "license": "MIT",
       "dependencies": {
         "has-symbols": "^1.0.3"

package.json

@@ -42,6 +42,7 @@
   "author": "John Stroh <john.stroh.nz@pm.me>",
   "license": "Apache-2.0",
   "dependencies": {
+    "axios": "^1.12.2",
     "bcrypt": "^5.1.1",
     "cookie-parser": "^1.4.7",
     "cors": "^2.8.5",

src/services/DeepL.service.js

@@ -51,16 +51,21 @@ class DeepLService {
     } = options;
 
     try {
+      const payload = {
+        text: [text],
+        source_lang: sourceLang,
+        target_lang: targetLang.toUpperCase(),
+        tag_handling: tagHandling
+      };
+
+      // Add formality only for languages that support it (DE, FR, IT, ES, NL, PL, PT, RU)
+      if (['DE', 'FR', 'IT', 'ES', 'NL', 'PL', 'PT', 'RU'].includes(targetLang.toUpperCase()) && formality !== 'default') {
+        payload.formality = formality;
+      }
+
       const response = await axios.post(
         `${this.apiUrl}/translate`,
-        {
-          text: [text],
-          source_lang: sourceLang,
-          target_lang: targetLang.toUpperCase(),
-          preserve_formatting: preserveFormatting ? '1' : '0',
-          formality: formality,
-          tag_handling: tagHandling
-        },
+        payload,
         {
           headers: {
             'Authorization': `DeepL-Auth-Key ${this.apiKey}`,