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/exploiting-insecure-deserialization/scripts/agent.py

@@ -89,7 +89,6 @@ def scan_response_body(url: str, method: str = "GET",
 def test_java_deserialization(url: str, cookie_name: str,
                                callback_host: str) -> dict:
     """Test for Java deserialization using a URLDNS-style detection payload."""
-    import struct
     dns_url = f"http://{callback_host}/java-deser-test"
     urldns_marker = base64.b64encode(
         JAVA_MAGIC + b"\x00\x00\x00" + dns_url.encode()