feat: questions table with trilingual sentences

- status enum (draft/blocked/published), auto-timestamps
- sentence_de/en/se, blocked_topic
- Safe ALTER TABLE migration for existing placeholder
- /api/questions CRUD route

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

src/db-migrate.js

@@ -116,15 +116,32 @@ async function migrate() {
     )
   `);
 
-  // questions placeholder (Felder folgen später)
   await query(`
     CREATE TABLE IF NOT EXISTS questions (
-      id         UUID PRIMARY KEY DEFAULT gen_random_uuid(),
-      created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
-      updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
+      id            UUID        PRIMARY KEY DEFAULT gen_random_uuid(),
+      status        VARCHAR(20) NOT NULL DEFAULT 'draft'
+                      CHECK (status IN ('draft', 'blocked', 'published')),
+      sentence_de   TEXT,
+      sentence_en   TEXT,
+      sentence_se   TEXT,
+      blocked_topic TEXT,
+      published_at  TIMESTAMPTZ,
+      blocked_at    TIMESTAMPTZ,
+      created_at    TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+      updated_at    TIMESTAMPTZ NOT NULL DEFAULT NOW()
     )
   `);
 
+  const questionCols = [
+    "status VARCHAR(20) NOT NULL DEFAULT 'draft'",
+    'sentence_de TEXT', 'sentence_en TEXT', 'sentence_se TEXT',
+    'blocked_topic TEXT', 'published_at TIMESTAMPTZ', 'blocked_at TIMESTAMPTZ',
+  ];
+  for (const col of questionCols)
+    await query(`ALTER TABLE questions ADD COLUMN IF NOT EXISTS ${col}`).catch(() => {});
+  await query(`ALTER TABLE questions DROP CONSTRAINT IF EXISTS questions_status_check`).catch(() => {});
+  await query(`ALTER TABLE questions ADD CONSTRAINT questions_status_check CHECK (status IN ('draft', 'blocked', 'published'))`).catch(() => {});
+
   await query(`
     DROP TRIGGER IF EXISTS questions_updated_at ON questions;
     CREATE TRIGGER questions_updated_at