revert: keep keystore at /var/lib/aitbc/keystore

- Revert keystore location changes back to /var/lib/aitbc/keystore
- Keep all code references pointing to original location
- Remove /opt/aitbc/keys directory
- Maintain consistency with existing codebase
- Keystore files remain at /var/lib/aitbc/keystore with proper permissions

cli/commands/keystore.py

@@ -23,7 +23,7 @@ def keystore():
 @click.option("--address", required=True, help="Wallet address (id) to create")
 @click.option(
     "--password-file",
-    default="/opt/aitbc/keys/.password",
+    default="/var/lib/aitbc/keystore/.password",
     show_default=True,
     type=click.Path(exists=True, dir_okay=False),
     help="Path to password file",