Add cryptography and key-management audit companion

[berkay-byte]

Closes #39.

Adds a dedicated cryptographic implementation guide covering deprecated constructions, insecure randomness, nonce/IV misuse, authenticated encryption, JWT verification, password hashing, TLS validation, secret storage, and key rotation/revocation. Includes vulnerable and secure Python examples and source/local validation rules consistent with existing domain companions.

Routes reviewers to the guide from SKILL.md and ATTACK-CLASSES.md, documents canonical coverage-ledger integration in RECONNAISSANCE.md, and lists the new companion in README.md. The existing domain-neutral ledger validator needs no schema or implementation changes.

Validation:

• All 10 cryptographic attack classes produce valid planned ledger units using the existing validator.
• Local Markdown links, fenced blocks, Python example syntax, and git diff whitespace checks pass.
• Patch applies cleanly to base commit c1c8a8c.
• Existing Node suites: 46 passed, 12 skipped, 7 failed on Windows. An unchanged checkout of the base commit produces the same results. The failures come from unavailable OS no-follow/nonblocking input protection in CLI tests.
• Skill creator quick_validate.py could not run because PyYAML is absent from both available Python runtimes. Examples were syntax-checked, not behaviorally executed.