Release/r3.1.0

[jaymengxy]

Closes #2803

Summary

• Add KeyStorageManager and KeyStorageMigration to store mnemonic / private key / Android Keystore prefix independently of the Account object
• Update WalletCreationHelper, CryptoProviderManager, AuthBridgeHandler, NativeFRWBridge, KeyStoreRestoreViewModel to write to / read from new storage
• Add buildLocalKeyAccounts() in AccountManager to surface recoverable accounts whose key survives but Account cache was lost
• Bump flow-wallet-android 0.2.1 → 0.2.4 (picks up SeedPhraseKey.load() and CryptoProviderKey identifier storage helpers)
• Fix: switch current account set

Test Plan

• New wallet creation stores key in frw_sp_storage/ and survives app-cache clear
• Private key import stores key in frw_pk_storage/ and survives app-cache clear
• Android Keystore prefix stored in frw_akp_storage/ and wallet recreates correctly
• Migration runs once on first launch with existing accounts and is idempotent
• Orphaned-key accounts appear in account switcher after clearing Account cache
• Switch via LocalSwitchAccount completes login and re-adds account normally

🤖 Generated with Claude Code

[github-actions]

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