refactor(intel): migrate AttackerIntel JSON-string columns to native SQLAlchemy JSON

Five list columns (greynoise_tags, abuseipdb_categories, threatfox_threat_types,
threatfox_ioc_types, threatfox_malware_families) and four dict columns
(*_raw) are now Column(JSON) with list/dict type annotations and
default_factory=list/dict. Providers return native Python objects; the
application-layer json.dumps/json.loads round-trip and _decode_json_list
helpers are gone. to_intel_event_payload() reads columns directly.

Also caps pytest xdist at -n 4 and excludes tests/api from norecursedirs
to prevent schemathesis workers from OOM-killing the dev loop.

decnet/intel/feodo.py

@@ -13,7 +13,6 @@ of attacker IPs map to a single network round-trip per refresh window.
 """
 from __future__ import annotations
 
-import json
 import time
 from datetime import datetime, timezone
 from typing import Any, Optional
@@ -94,7 +93,7 @@ class FeodoProvider(IntelProvider):
                 column_updates={
                     "feodo_listed": False,
                     "feodo_malware_family": None,
-                    "feodo_raw": "{}",
+                    "feodo_raw": {},
                     "feodo_queried_at": datetime.now(timezone.utc),
                 },
             )
@@ -108,7 +107,7 @@ class FeodoProvider(IntelProvider):
             column_updates={
                 "feodo_listed": True,
                 "feodo_malware_family": family,
-                "feodo_raw": json.dumps(entry),
+                "feodo_raw": entry,
                 "feodo_queried_at": datetime.now(timezone.utc),
             },
         )