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-aes-encryption-for-data-at-rest/SKILL.md

@@ -47,7 +47,7 @@ Never use raw passwords as encryption keys. Always derive keys using:
 - Generate nonces using `os.urandom()` (CSPRNG)
 - Store nonce alongside ciphertext (it is not secret)
 
-## Implementation Steps
+## Workflow
 
 1. Install the `cryptography` library: `pip install cryptography`
 2. Generate or derive an encryption key