Initial commit : API Node.js + PostgreSQL + sync service Docker

- API Express/pg connectée à PostgreSQL (converti depuis mssql)
- 8 routes : articles, fournisseurs, commandes, stock, mouvements, performance, schema, sync
- Service sync nightly (mssql → pg, cron 3h00)
- Docker Compose : postgres + api + sync + frpc (tunnel sortant)
- Schéma PostgreSQL 17 tables dans postgres/init.sql

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

sync/db.js

@@ -0,0 +1,48 @@
+require('dotenv').config();
+const sql = require('mssql');
+const { Pool } = require('pg');
+
+const mssqlConfig = {
+  server:   process.env.DB_HOST,
+  port:     parseInt(process.env.DB_PORT) || 1433,
+  database: process.env.DB_NAME,
+  user:     process.env.DB_USER,
+  password: process.env.DB_PASSWORD,
+  options: {
+    encrypt: false,
+    trustServerCertificate: true,
+    readOnlyIntent: true,
+  },
+  pool: { max: 5, min: 0, idleTimeoutMillis: 30000 },
+};
+
+let mssqlPool = null;
+let pgPool = null;
+
+async function getMssql() {
+  if (!mssqlPool) {
+    mssqlPool = await sql.connect(mssqlConfig);
+  }
+  return mssqlPool;
+}
+
+function getPg() {
+  if (!pgPool) {
+    pgPool = new Pool({
+      host:     process.env.PG_HOST || 'postgres',
+      port:     parseInt(process.env.PG_PORT) || 5432,
+      database: process.env.PG_DB,
+      user:     process.env.PG_USER,
+      password: process.env.PG_PASSWORD,
+      max: 5,
+    });
+  }
+  return pgPool;
+}
+
+async function closeAll() {
+  if (mssqlPool) { await mssqlPool.close(); mssqlPool = null; }
+  if (pgPool)    { await pgPool.end();      pgPool = null; }
+}
+
+module.exports = { getMssql, getPg, closeAll, sql };