Production hardening: security fixes, code quality, 724 skills complete

- Fix 25 shell=True subprocess calls with list-based commands
- Fix 49 verify=False in defensive skills (env-var override)
- Add timeout to 231 HTTP/subprocess/socket calls
- Fix 6 SQL injection patterns with whitelist validation
- Replace 8 __import__() with standard imports
- Remove 701 unused imports across 442 files
- Add authorized-testing disclaimers to all offensive skills
- Complete 11 incomplete skill directories
- Expand 10 stub SKILL.md files with full content
- Fix 2 YAML parse errors in frontmatter
- Fix 5 pre-existing syntax errors
- Convert 22 hardcoded paths/ports to environment variables
- Back up 21 redundant skill pairs to .bak
- Fix 2 global declaration errors
- 724/724 skills with full folder anatomy (SKILL.md + agent.py + api-reference.md + LICENSE)
- 0 compile errors across all 724 agent.py files

skills/implementing-network-access-control/scripts/agent.py

@@ -4,8 +4,6 @@
 import json
 import sys
 import argparse
-import socket
-import struct
 from datetime import datetime
 from collections import Counter
 
@@ -18,8 +16,7 @@ except ImportError:
     sys.exit(1)
 
 try:
-    from pysnmp.hlapi import (getCmd, nextCmd, SnmpEngine, CommunityData,
-                               UdpTransportTarget, ContextData, ObjectType, ObjectIdentity)
+    from pysnmp.hlapi import nextCmd, SnmpEngine, CommunityData, UdpTransportTarget, ContextData, ObjectType, ObjectIdentity
     HAS_SNMP = True
 except ImportError:
     HAS_SNMP = False