flutter_secure_storage_darwin

• Raised minimum iOS deployment target from 12.0 to 13.0 to fix Swift compiler errors when building with Swift Package Manager. CryptoKit (used for Secure Enclave support) requires iOS 13.0+.

• Fixed secStoreAvailabilitySink not being called when protected data availability changes.
• Fixed kSecUseDataProtectionKeychain being added to Keychain queries unconditionally; it is now only set when useDataProtectionKeychain is explicitly enabled.

• Fixed iOS build by updating availability annotation for Secure Enclave methods from iOS 11.3 to iOS 13.0.

• Added useSecureEnclave support for iOS and macOS to store encryption keys in the device's Secure Enclave for hardware-backed security.
• Use shared LAContext to reuse biometric authentication across Secure Enclave operations, avoiding double authentication prompts.
• Secure Enclave keys now use hardcoded .privateKeyUsage access control, preventing "ACL operation is not allowed" errors.

Fixes:

• Fixed kSecAttrSynchronizable being silently dropped when no access control flags are set.
• Fixed readAll to correctly return Secure Enclave items.
• Fixed macOS options keys alignment with iOS options.
• Added plain-text fallback when a Secure Enclave wrapped key is missing.

• Remove keys regardless of synchronizable state or accessibility constraints.

• Fix warnings with Privacy Manifest

This package combines flutter_secure_storage_macos together with the ios part of flutter_secure_storage.

Other changes:

• Code has been rebuild from the ground up
• Lots of missing attributes have been added to the IOSOptions and MacOsOptions classes.