test(quic): add extended coverage tests for crypto module (#1002)

Adds 88 deterministic, public-API-only unit tests targeting the
lower-coverage branches in src/protocols/quic/crypto.cpp. Covers:

- HKDF extract/expand/expand_label edge cases including empty-salt
  and empty-IKM error paths, zero-length expand, and label/context
  isolation
- initial_keys::derive for QUIC v1 and v2 salts, version divergence,
  empty and max-length DCIDs, and secret propagation into keys
- derive_keys with the is_client_keys flag verified as no-op
- Packet protection AEAD round-trip across many packet numbers,
  empty and large payloads, and varying header sizes
- Unprotect failure paths: truncated packet, modified header,
  wrong packet number, wrong key, wrong IV, corrupted tag,
  corrupted ciphertext
- Header protection mask: short-sample rejection, key/sample
  isolation, determinism
- Header protection protect/unprotect round-trip across long and
  short headers with packet number lengths 1-4, self-inverse XOR
- quic_crypto public surface: set_keys monotonic level raising,
  ALPN wire-format rejection of overlong protocols, 0-RTT ticket
  and early-data gates, update_keys pre-handshake rejection, move
  semantics preserving keys
- quic_keys / key_pair is_valid, clear, and equality operators

All tests run in under one second total with no real network IO
and no TLS handshake.

Closes #993

Author: kcenon

tests/CMakeLists.txt

@@ -4649,6 +4649,7 @@ message(STATUS "WebSocket socket unit tests enabled (Issue #968)")
 add_network_test(network_session_ticket_store_test unit/session_ticket_store_test.cpp)
 add_network_test(network_quic_pmtud_controller_test unit/quic_pmtud_controller_test.cpp)
 add_network_test(network_quic_crypto_module_test unit/quic_crypto_test.cpp)
+add_network_test(network_quic_crypto_extended_test unit/quic_crypto_extended_test.cpp)
 add_network_test(network_quic_connection_module_test unit/quic_connection_test.cpp)
 add_network_test(network_quic_connection_extended_test unit/quic_connection_extended_test.cpp)
 add_network_test(network_quic_socket_construction_test unit/quic_socket_construction_test.cpp)