Don't save the value of password inputs in the snapshot

[rigtorp]

Currently <input type="password"> have their values saved in the snapshot.

For example:

              - generic [ref=e1611]:
                - textbox "Password" [active] [ref=e1612]:
                  - /placeholder: Enter your password
                  - text: hunter2

It would be useful to dump a placeholder or omit it by default.

[dgozman]

@rigtorp You can use PLAYWRIGHT_MCP_SECRETS_FILE environment variable to provide a dotenv-formatted file, and secrets will be automatically redacted from the output. Let me know whether this works for you.