release: v1.1.0 with improved state management, security, and concurrency

[harrytmthy]

Summary

This PR finalizes the v1.1.0 release of SafeBox, delivering major upgrades in lifecycle coordination, cryptographic safety, and multi-threaded performance.

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Highlights

Lifecycle Management

• SafeBoxStateManager: Tracks internal states (STARTING, WRITING, IDLE, CLOSED) to ensure deterministic transitions even under concurrent writes. Prevents invalid state emissions after closure. (#17)
• Global and Per-instance Observability:
  • SafeBoxGlobalStateObserver monitors file-level state transitions.
  • SafeBoxStateListener allows per-instance state tracking.
    (#12)

Security Hardening

• XOR-based In-Memory Masking: SafeSecretKey is now XOR-masked using a SHA-256 mask to prevent raw DEK exposure in memory. (#23)
• On-demand Cipher Lifecycle: AesGcmCipherProvider now creates ciphers only when needed, minimizing sensitive memory retention. (#28)

Cryptographic Concurrency

• CipherPool: A coroutine-friendly, thread-safe pool for Cipher reuse. Supports load-factor-based scaling, ideal for parallel get() / put() workloads. (#25)
• SafeBoxExecutor: Internal executor used to schedule async tasks like CipherPool scaling. Designed for future extensibility. (#30)
• Concurrent Key Access: Both SafeSecretKey and SecureRandomKeyProvider now support multi-threaded access via atomic caching. (#26)

Stability & Compatibility

• BouncyCastleProvider is now conditionally injected only when ChaCha20 support is missing. Prevents unintentional overrides of external configurations. (#1)
• compileSdk bumped to 36, ensuring forward compatibility with the latest Android API surface. (#2)

Benchmark Update

• The README now includes updated v1.1.0 benchmark results, showcasing improvements in:
  • Init time
  • Put performance
  • Commit throughput
  • CipherPool efficiency

GitHub Sponsors & Metadata

• GitHub Sponsors is now enabled via FUNDING.yml
• README now includes:
  • Project badges: build status, license, version
  • A new collapsible encryption flow section for better readability