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/services/scheduler_service.py

@@ -0,0 +1,71 @@
+import logging
+from apscheduler.schedulers.asyncio import AsyncIOScheduler
+from apscheduler.triggers.interval import IntervalTrigger
+
+logger = logging.getLogger(__name__)
+
+_scheduler = None
+_is_running = False
+
+
+def init_scheduler():
+    """Initialize the APScheduler instance."""
+    global _scheduler
+    _scheduler = AsyncIOScheduler()
+    logger.info("Scheduler initialized")
+
+
+def start_scheduler(interval_minutes: int = 5):
+    """Start the scheduler with the given interval."""
+    global _is_running
+    if _scheduler is None:
+        init_scheduler()
+
+    # Remove existing job if any
+    if _scheduler.get_job("sync_job"):
+        _scheduler.remove_job("sync_job")
+
+    from . import sync_service
+
+    _scheduler.add_job(
+        sync_service.run_sync,
+        trigger=IntervalTrigger(minutes=interval_minutes),
+        id="sync_job",
+        name="GoMag Sync",
+        replace_existing=True
+    )
+
+    if not _scheduler.running:
+        _scheduler.start()
+
+    _is_running = True
+    logger.info(f"Scheduler started with interval {interval_minutes}min")
+
+
+def stop_scheduler():
+    """Stop the scheduler."""
+    global _is_running
+    if _scheduler and _scheduler.running:
+        if _scheduler.get_job("sync_job"):
+            _scheduler.remove_job("sync_job")
+        _is_running = False
+        logger.info("Scheduler stopped")
+
+
+def shutdown_scheduler():
+    """Shutdown the scheduler completely."""
+    global _scheduler, _is_running
+    if _scheduler and _scheduler.running:
+        _scheduler.shutdown(wait=False)
+    _scheduler = None
+    _is_running = False
+
+
+def get_scheduler_status():
+    """Get current scheduler status."""
+    job = _scheduler.get_job("sync_job") if _scheduler else None
+    return {
+        "enabled": _is_running,
+        "next_run": job.next_run_time.isoformat() if job and job.next_run_time else None,
+        "interval_minutes": int(job.trigger.interval.total_seconds() / 60) if job else None
+    }