feat: add Tumblr email scan module

[brunolm]

Adds an email-existence scan module for Tumblr.

How it works

• Scrapes the web app's API_TOKEN from the homepage, reads the X-Csrf header from GET /api/v2/radar, then POST /api/v2/register/account/validate with the email and a deliberately short password.
• This is a validation-only endpoint and the short password means no account is ever created and no email is sent.

Signal

• Registered → response.code == 2 ("User already exists") → Result.taken
• Not registered → response.code == 1030 (password-too-short — the email cleared the uniqueness check) → Result.available
• Neither → Result.error

Testing

• Verified live end-to-end: a registered address returns Registered, a random unregistered address returns Not Registered.
• Auto-discovered (no registry changes). Full test suite passes (only the pre-existing *_unreadable tests fail, and only on Windows).

[kaifcodec]

@brunolm I found an issue for which it was throwing,

[!] Tumblr (johndoe@gmail.com): Error (unexpected exception: <StreamReset stream_id:1, error_code:1, remote_reset:True>)

• Under HTTP/2, this triggers a (REFUSED_STREAM).
• Under HTTP/1.1, the server abruptly closes the connection, leading to a Server disconnected without sending a response exception.

So I refactored it with urllib because its simpler TLS handshake signature and socket wrapping do not trigger the same bot-protection filters on Tumblr's servers.