Add languages, user_names, users_public tables and routes; fix _se→_sv rename

- Fix broken rename migration array (sed had corrupted from values to _sv)
- Add languages table with status lifecycle and trilingual titles
- Add user_names table with unique lowercase index
- Add users_public table linking to user_names and languages (native/target)
- Wire all three new routes under /api/languages, /api/user-names, /api/users-public

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/index.js

@@ -35,6 +35,9 @@ app.use('/api/pairs', auth, require('./routes/pairs'));
 app.use('/api/questions', auth, require('./routes/questions'));
 app.use('/api/statements', auth, require('./routes/statements'));
 app.use('/api/blocklist', auth, require('./routes/blocklist'));
+app.use('/api/languages', auth, require('./routes/languages'));
+app.use('/api/user-names', auth, require('./routes/user-names'));
+app.use('/api/users-public', auth, require('./routes/users-public'));
 
 // 404
 app.use((req, res) => {