feat: add content senders and language settings components

- Implemented ContentSendersSettings component for managing trusted senders.
- Added LanguageSettings component to allow users to select their preferred language.
- Introduced minimal i18n support with locale detection and translation functions.
- Created a locale store using Zustand for managing locale state and persistence with AsyncStorage.
- Added a script to sync locale JSON files from the parent webmail repository.

scripts/sync-locales.mjs

@@ -0,0 +1,43 @@
+// Copy locale JSON files from the parent webmail repo into ./locales/.
+// Run from the RN repo root: `node scripts/sync-locales.mjs`.
+// In environments where the parent repo isn't checked out (e.g. CI clone of
+// the standalone RN repo), this is a no-op — vendored files stay as-is.
+import { readdir, mkdir, copyFile, stat } from 'node:fs/promises';
+import { existsSync } from 'node:fs';
+import { join, dirname } from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const __dirname = dirname(fileURLToPath(import.meta.url));
+const RN_LOCALES = join(__dirname, '..', 'locales');
+const WEBMAIL_LOCALES = join(__dirname, '..', '..', '..', 'locales');
+
+if (!existsSync(WEBMAIL_LOCALES)) {
+  console.log(`No webmail locales at ${WEBMAIL_LOCALES} — skipping (vendored files will be used).`);
+  process.exit(0);
+}
+
+async function copyDir(src, dest) {
+  await mkdir(dest, { recursive: true });
+  for (const entry of await readdir(src, { withFileTypes: true })) {
+    const s = join(src, entry.name);
+    const d = join(dest, entry.name);
+    if (entry.isDirectory()) {
+      await copyDir(s, d);
+    } else if (entry.isFile() && entry.name.endsWith('.json')) {
+      await copyFile(s, d);
+    }
+  }
+}
+
+const langs = (await readdir(WEBMAIL_LOCALES, { withFileTypes: true }))
+  .filter((e) => e.isDirectory())
+  .map((e) => e.name);
+
+let copied = 0;
+for (const lang of langs) {
+  const src = join(WEBMAIL_LOCALES, lang);
+  const dest = join(RN_LOCALES, lang);
+  await copyDir(src, dest);
+  copied++;
+}
+console.log(`Synced ${copied} locale(s) from ${WEBMAIL_LOCALES} → ${RN_LOCALES}`);