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/routes/questions.js

@@ -31,11 +31,11 @@ router.get('/:id', async (req, res, next) => {
 // POST /api/questions
 router.post('/', async (req, res, next) => {
   try {
-    const { sentence_de, sentence_en, sentence_se, blocked_topic } = req.body;
+    const { sentence_de, sentence_en, sentence_sv, blocked_topic } = req.body;
     const result = await query(
-      `INSERT INTO questions (sentence_de, sentence_en, sentence_se, blocked_topic)
+      `INSERT INTO questions (sentence_de, sentence_en, sentence_sv, blocked_topic)
        VALUES ($1, $2, $3, $4) RETURNING *`,
-      [sentence_de || null, sentence_en || null, sentence_se || null, blocked_topic || null]
+      [sentence_de || null, sentence_en || null, sentence_sv || null, blocked_topic || null]
     );
     res.status(201).json(result.rows[0]);
   } catch (err) { next(err); }
@@ -44,7 +44,7 @@ router.post('/', async (req, res, next) => {
 // PATCH /api/questions/:id
 router.patch('/:id', async (req, res, next) => {
   try {
-    const allowed = ['status', 'sentence_de', 'sentence_en', 'sentence_se',
+    const allowed = ['status', 'sentence_de', 'sentence_en', 'sentence_sv',
                      'blocked_topic', 'published_at', 'blocked_at'];
     const fields = Object.keys(req.body).filter(k => allowed.includes(k));
     if (!fields.length) return res.status(400).json({ error: 'No valid fields provided' });