test: Wave 14 - comprehensive adapter and facade tests (#40)

* test: comprehensive integration tests for rustcrypto and rustls adapters

rustcrypto (31 tests):
- RSA/ECDSA/Ed25519/HMAC sign-verify round trips
- Wrong message verification failures
- Deterministic key reproduction
- Different labels produce different keys
- RSA-4096 key conversion
- Cross-curve panic tests (p256/p384)
- HMAC SHA-256/384/512 compute and verify
- Tag length verification
- Debug safety (no key material leakage)
- Cross-adapter all-types from same factory
- Deterministic all-types stability

rustls (20 tests):
- Certificate/key DER conversion correctness
- Chain structure (leaf + intermediate)
- Root certificate matching
- RSA/ECDSA/Ed25519 private key conversion
- TLS handshake with chain
- mTLS handshake
- Wrong SNI fails handshake
- Cross-CA fails handshake
- Deterministic chain and self-signed reproduction
- Different seeds produce different chains
- Debug safety for chains and self-signed certs

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* test: facade e2e and property-based tests

facade_e2e.rs (18 tests):
- Deterministic reproduction for RSA, ECDSA, Ed25519, HMAC, token
- Order-independent derivation (ABC vs CBA generation order)
- Different labels produce different keys
- Debug safety (no PEM markers leaked)
- Negative fixture CorruptPem variants
- PEM format well-formedness
- Factory mode verification
- Seed round-trip

prop_tests.rs (10 tests):
- Property-based determinism for RSA, ECDSA, Ed25519, HMAC, token
- PEM well-formedness under random seeds
- HMAC secret length matches spec
- Token prefix invariant
- Different seeds produce different ECDSA keys
- Corrupt PEM never returns original

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* fix: remove unused testutil imports from facade e2e and prop tests

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* style: fix formatting for CI

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

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Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: EffortlessSteven