Adds a Configuration property, defaulted to enabled, and a checkbox in
the Chat settings tab's Behaviour section. Strings live in HellionStrings
so DE/EN stays in sync. Defaults aligned with our 'discoverable by
default, hidden by user choice' convention. Schema stays at v17 — the
new boolean is additive, the default constructor covers existing configs.
JonKazama-Hellion
679b8f0f5e