PR: Fix Keystore Wallet

Summary

This PR strengthens keystore security and improves wallet UI behavior by requiring password authentication before key deletion and fixing several UX issues in the wallet interface.

Changes

Security: Password-Protected Key Deletion

Previously, deleting a key from the keystore only required providing the address or nickname — no credential verification was needed. This meant any caller with access to the admin API could remove keys without proving ownership.

Key deletion now requires the caller to supply the correct password. The password is validated by attempting to decrypt the stored key before any deletion occurs. If the password is incorrect or missing, the operation is rejected with an error. This applies across all entry points: the Go library, the RPC admin endpoint, the CLI, and the wallet frontend.

The delete confirmation dialog in the wallet UI was updated accordingly — instead of asking the user to retype the wallet name, it now prompts for the wallet password, providing a more meaningful security check.

UX: Modal Auto-Close on Success

The Import Wallet and Create New Key modals on the Key Management page previously stayed open after a successful operation, requiring the user to manually dismiss them. Both modals now close automatically upon success.

UX: Escape Key Support for Governance Modals

The Poll Details and Proposal Details modals in the governance section did not respond to the Escape key. Both modals now listen for the Escape keypress and close accordingly, aligning them with standard modal behavior.

API & Config Updates

The keystore delete endpoint configuration was updated to send address and password in the request body instead of nickname, reflecting the new backend requirements. The RPC README documentation was updated to describe the new required password field.