fix(macos): Keychain secrets fail without keychain-access-groups; use the login keychain #1586

Problem

flutter_secure_storage_darwin defaults to usesDataProtectionKeychain: true (FlutterSecureStorageDarwinPlugin.swift:180), which needs the keychain-access-groups entitlement. None of DebugProfile.entitlements, Release.entitlements, ReleaseSigned.entitlements declare it, and lib/core/storage/connection_secrets_store.dart uses const FlutterSecureStorage() with no macOS options.

Expected on macOS: errSecMissingEntitlement (-34018) on write/read, surfaced as SecretsStoreUnavailableException ("Could not read the saved credentials from the system keyring").

Fix

Do not add keychain-access-groups to ReleaseSigned.entitlements: it is a restricted entitlement that needs a provisioning profile for Developer ID, and the app would fail to launch. Instead pass MacOsOptions(usesDataProtectionKeychain: false) (mOptions) so the file-based login keychain is used.

Tasks

• Reproduce on a real Mac (debug, unsigned release, signed release).
• Set mOptions: MacOsOptions(usesDataProtectionKeychain: false).
• Check existing installs: items written with the data protection keychain (if any) must still be readable, or migrated.
• Test on signed + notarized and on ad-hoc builds.

Found in the macOS review; confirm on device first.