Integrate Cryptography into QueueClient

[pvandervelde]

Context

• Specification: docs/spec/modules/cryptography.md section 6
• Location: src/client.rs modifications
• Integration: Add optional encryption to send/receive operations
• Configuration: Add crypto_provider and plaintext_policy to QueueClientBuilder
• Backward Compatibility: Encryption is optional, no breaking changes
• Assertions: docs/spec/assertions.md fix(cliff): hardcode github owner/repo in footer template #30, chore(deps): bump openssl from 0.10.77 to 0.10.78 #36

Subtasks

• 23.1 Add optional crypto_provider field to QueueClient
• 23.2 Add optional plaintext_policy field to QueueClient (defaults to Allow)
• 23.3 Modify send() to encrypt if crypto_provider present
• 23.4 Modify receive() to detect and decrypt if encrypted
• 23.5 Add QueueClientBuilder methods: with_encryption(provider, policy)
• 23.6 Add debug mode support (encryption can be disabled, Assertion chore(deps): bump openssl from 0.10.77 to 0.10.78 #36)
• 23.7 Update QueueClient documentation with encryption examples
• 23.8 Add integration tests for encrypted send/receive workflow

Phase

Phase 5: Cryptography Module Implementation (Task 23.0)