fix(ci): lazy-import duckdb to prevent pytest hang

DuckDB spawns non-daemon background threads on import. Since
analytics.py was imported at module level (transitively by the
test suite), these threads kept the pytest process alive after
all tests completed. Moving the import into open_analytics_db()
means duckdb is only loaded when actually needed.

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

web/src/padelnomics/analytics.py

@@ -14,14 +14,14 @@ import os
 from pathlib import Path
 from typing import Any
 
-import duckdb
-
-_conn: duckdb.DuckDBPyConnection | None = None
+_conn = None  # duckdb.DuckDBPyConnection | None — lazy import
 _DUCKDB_PATH = os.environ.get("SERVING_DUCKDB_PATH", "data/analytics.duckdb")
 
 
 def open_analytics_db() -> None:
     """Open the DuckDB connection. Call once at app startup."""
+    import duckdb
+
     global _conn
     path = Path(_DUCKDB_PATH)
     if not path.exists():