frontend: add French translation and language i18n keys

Register `fr` in the i18n config (resources + supportedLngs) and add a full
French translation (locales/fr/translation.json) with exact key parity to
English (1661 keys; placeholders and plural suffixes preserved). Also adds the
shared `common.pagination.*` keys, `settings.version.checkNow`, and
`settings.profile.language.*`, and drops the now-unused `patients.pagination.*`.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/lib/i18n/config.ts

@@ -5,14 +5,19 @@ import LanguageDetector from "i18next-browser-languagedetector";
 import { initReactI18next } from "react-i18next";
 
 import en from "./locales/en/translation.json";
+import fr from "./locales/fr/translation.json";
 
 export const defaultNS = "translation";
 
 // Add new languages here (and a matching JSON under locales/<lng>/translation.json).
 export const resources = {
   en: { translation: en },
+  fr: { translation: fr },
 } as const;
 
+// Languages offered in the Settings → Profile switcher (label rendered there).
+export const supportedLanguages = ["en", "fr"] as const;
+
 if (!i18n.isInitialized) {
   i18n
     .use(LanguageDetector)
@@ -21,8 +26,8 @@ if (!i18n.isInitialized) {
       resources,
       defaultNS,
       fallbackLng: "en",
-      // Only `en` exists today; keep this in sync with `resources` as languages grow.
-      supportedLngs: ["en"],
+      // Keep this in sync with `resources` as languages grow.
+      supportedLngs: ["en", "fr"],
       interpolation: { escapeValue: false },
       detection: {
         order: ["localStorage", "navigator", "htmlTag"],

frontend/lib/i18n/locales/en/translation.json

@@ -6,7 +6,14 @@
     "signIn": "Sign in",
     "signUp": "Sign up",
     "backToSignIn": "Back to sign in",
-    "addedByAi": "Added by AI"
+    "addedByAi": "Added by AI",
+    "pagination": {
+      "label": "Pages",
+      "previous": "Previous",
+      "next": "Next",
+      "page": "Page {{page}}",
+      "summary": "Showing {{from}}–{{to}} of {{total}}"
+    }
   },
   "auth": {
     "login": {
@@ -222,13 +229,6 @@
     "loading": "Loading patients…",
     "empty": "No patients found.",
     "loadError": "Failed to load patients.",
-    "pagination": {
-      "label": "Patient pages",
-      "previous": "Previous",
-      "next": "Next",
-      "page": "Page {{page}}",
-      "summary": "Showing {{from}}–{{to}} of {{total}}"
-    },
     "columns": {
       "name": "Name",
       "mrn": "MRN",
@@ -1520,6 +1520,7 @@
       "current": "Current version",
       "latest": "Latest release",
       "checking": "Checking for updates…",
+      "checkNow": "Check for updates",
       "upToDate": "Up to date",
       "updateAvailable": "Update available",
       "offline": "Couldn't reach the update server",
@@ -1683,6 +1684,13 @@
       "professionalLinks": "Professional links",
       "professionalLinksHint": "Registry or institutional profiles used to verify your identity. They are never shown to patients.",
       "addLink": "Add link",
+      "language": {
+        "title": "Language",
+        "description": "The language temetro's interface is shown in on this device.",
+        "label": "Display language",
+        "en": "English",
+        "fr": "Français"
+      },
       "patientNotifications": "Patient notifications",
       "patientNotificationsDescription": "Emails sent to patients about their records, results, and pending approvals",
       "accountNotifications": "Account notifications",