feat: auto-migrate SQLite data to Postgres on first deploy

- Add trumpsignal.db to git (one-time migration source)
- entrypoint.sh detects empty Postgres and runs migration automatically
- scripts/migrate_sqlite_to_postgres.py: posts, subscriptions, bot_trades
- Add psycopg2-binary to requirements for migration script

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

entrypoint.sh

@@ -4,5 +4,35 @@ set -e
 echo "[entrypoint] Running Alembic migrations..."
 alembic upgrade head
 
+# One-time migration: if trumpsignal.db exists and posts table is empty,
+# migrate SQLite data into Postgres then remove the db file.
+if [ -f "trumpsignal.db" ]; then
+    echo "[entrypoint] Found trumpsignal.db — checking if migration needed..."
+    POST_COUNT=$(python -c "
+import asyncio, os
+os.environ.setdefault('DATABASE_URL', '')
+import psycopg2
+url = os.environ.get('DATABASE_URL','').replace('+asyncpg','')
+try:
+    conn = psycopg2.connect(url)
+    cur = conn.cursor()
+    cur.execute('SELECT COUNT(*) FROM posts')
+    print(cur.fetchone()[0])
+    conn.close()
+except Exception as e:
+    print('0')
+" 2>/dev/null || echo "0")
+
+    if [ "$POST_COUNT" = "0" ]; then
+        echo "[entrypoint] Postgres is empty — running SQLite migration..."
+        python scripts/migrate_sqlite_to_postgres.py
+        echo "[entrypoint] Migration done. Removing trumpsignal.db..."
+        rm -f trumpsignal.db
+    else
+        echo "[entrypoint] Postgres already has data (${POST_COUNT} posts) — skipping migration."
+        rm -f trumpsignal.db
+    fi
+fi
+
 echo "[entrypoint] Starting API server..."
 exec uvicorn app.main:app --host 0.0.0.0 --port 8000