Feature request: Make the Tor exit node configurable

[sae13]

Feature description

Please add an option to configure the Tor exit node used by Aether. Users should be able to select the desired exit country and, if feasible, provide a Tor relay fingerprint (equivalent to Tor's ExitNodes setting).

Motivation

A configurable exit node is useful when a service requires traffic to originate from a particular country or when users need predictable routing behavior.

Suggested behavior

• Add an optional exit-node setting in the configuration/UI.
• Accept a country code (for example, {de}) and optionally a relay fingerprint.
• Keep Tor's automatic exit selection as the default when the setting is empty.
• Optionally expose strict enforcement (equivalent to StrictNodes 1) so Tor fails instead of silently choosing another country/node when the requested exit is unavailable.