fix(deploy): mirror frontend runtime deps into the root package.json

The o2switch nodevenv/Passenger setup only installs a single
package.json/node_modules (root), so npm install --prefix frontend
never actually populates frontend/node_modules there. Node's module
resolution walks up from frontend/src to the root node_modules, so
adding react-router-dom, react-i18next, i18next, and
@phosphor-icons/react to root's dependencies (react/react-dom were
already present) lets the production vite build resolve them without
needing a second node_modules tree.

package.json

@@ -15,6 +15,7 @@
     "deploy": "npm install --include=dev && npm run prisma-migration && npm run build && npm run worker-restart"
   },
   "dependencies": {
+    "@phosphor-icons/react": "^2.1.10",
     "@prisma/client": "^6.19.3",
     "docx": "^9.7.1",
     "dotenv": "^17.4.2",
@@ -25,6 +26,7 @@
     "fonteditor-core": "^2.6.3",
     "fontkit": "^2.0.4",
     "heic-convert": "^2.1.0",
+    "i18next": "^26.3.6",
     "icojs": "^1.0.0",
     "mammoth": "^1.12.0",
     "markdown-it": "^15.0.0",
@@ -36,6 +38,8 @@
     "puppeteer": "^25.4.0",
     "react": "^19.2.8",
     "react-dom": "^19.2.8",
+    "react-i18next": "^17.0.11",
+    "react-router-dom": "^7.18.2",
     "sharp": "^0.35.3",
     "turndown": "^7.2.4",
     "uuid": "^14.0.1"