feat: add FastAPI admin dashboard with sync orchestration and test suite

Replace Flask admin with FastAPI app (api/app/) featuring:
- Dashboard with stat cards, sync control, and history
- Mappings CRUD for ARTICOLE_TERTI with CSV import/export
- Article autocomplete from NOM_ARTICOLE
- SKU pre-validation before import
- Sync orchestration: read JSONs -> validate -> import -> log to SQLite
- APScheduler for periodic sync from UI
- File logging to logs/sync_comenzi_YYYYMMDD_HHMMSS.log
- Oracle pool None guard (503 vs 500 on unavailable)

Test suite:
- test_app_basic.py: 30 tests (imports + routes) without Oracle
- test_integration.py: 9 integration tests with Oracle

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

api/app/routers/validation.py

@@ -0,0 +1,111 @@
+import csv
+import io
+from fastapi import APIRouter
+from fastapi.responses import StreamingResponse
+
+from ..services import order_reader, validation_service
+from ..database import get_sqlite
+
+router = APIRouter(prefix="/api/validate", tags=["validation"])
+
+@router.post("/scan")
+async def scan_and_validate():
+    """Scan JSON files and validate all SKUs."""
+    orders, json_count = order_reader.read_json_orders()
+
+    if not orders:
+        return {"orders": 0, "json_files": json_count, "skus": {}, "message": "No orders found"}
+
+    all_skus = order_reader.get_all_skus(orders)
+    result = validation_service.validate_skus(all_skus)
+    importable, skipped = validation_service.classify_orders(orders, result)
+
+    # Track missing SKUs in SQLite
+    db = await get_sqlite()
+    try:
+        for sku in result["missing"]:
+            # Find product name from orders
+            product_name = ""
+            for order in orders:
+                for item in order.items:
+                    if item.sku == sku:
+                        product_name = item.name
+                        break
+                if product_name:
+                    break
+
+            await db.execute("""
+                INSERT OR IGNORE INTO missing_skus (sku, product_name)
+                VALUES (?, ?)
+            """, (sku, product_name))
+        await db.commit()
+    finally:
+        await db.close()
+
+    return {
+        "json_files": json_count,
+        "total_orders": len(orders),
+        "total_skus": len(all_skus),
+        "importable": len(importable),
+        "skipped": len(skipped),
+        "skus": {
+            "mapped": len(result["mapped"]),
+            "direct": len(result["direct"]),
+            "missing": len(result["missing"]),
+            "missing_list": sorted(result["missing"])
+        },
+        "skipped_orders": [
+            {
+                "number": order.number,
+                "customer": order.billing.company_name or f"{order.billing.firstname} {order.billing.lastname}",
+                "items_count": len(order.items),
+                "missing_skus": missing
+            }
+            for order, missing in skipped[:50]  # limit to 50
+        ]
+    }
+
+@router.get("/missing-skus")
+async def get_missing_skus():
+    """Get all tracked missing SKUs."""
+    db = await get_sqlite()
+    try:
+        cursor = await db.execute("""
+            SELECT sku, product_name, first_seen, resolved, resolved_at
+            FROM missing_skus
+            ORDER BY resolved ASC, first_seen DESC
+        """)
+        rows = await cursor.fetchall()
+        return {
+            "missing_skus": [dict(row) for row in rows],
+            "total": len(rows),
+            "unresolved": sum(1 for r in rows if not r["resolved"])
+        }
+    finally:
+        await db.close()
+
+@router.get("/missing-skus-csv")
+async def export_missing_skus_csv():
+    """Export missing SKUs as CSV."""
+    db = await get_sqlite()
+    try:
+        cursor = await db.execute("""
+            SELECT sku, product_name, first_seen, resolved
+            FROM missing_skus WHERE resolved = 0
+            ORDER BY first_seen DESC
+        """)
+        rows = await cursor.fetchall()
+    finally:
+        await db.close()
+
+    output = io.StringIO()
+    writer = csv.writer(output)
+    writer.writerow(["sku", "product_name", "first_seen"])
+    for row in rows:
+        writer.writerow([row["sku"], row["product_name"], row["first_seen"]])
+
+    return StreamingResponse(
+        io.BytesIO(output.getvalue().encode("utf-8-sig")),
+        media_type="text/csv",
+        headers={"Content-Disposition": "attachment; filename=missing_skus.csv"}
+    )