feat: move terminal settings, look and ssh tools into ssh-terminal plugin

plugins/ssh-terminal/tests/frontend/settings/tri-state.test.ts

@@ -0,0 +1,17 @@
+import { describe, expect, it } from "vitest";
+import {
+  fromTriState,
+  toTriState,
+} from "../../../src/frontend/settings/tri-state";
+
+describe("tri-state", () => {
+  it("keeps unset booleans distinct from false", () => {
+    expect(toTriState(undefined)).toBe("inherit");
+    expect(toTriState(true)).toBe("on");
+    expect(toTriState(false)).toBe("off");
+
+    expect(fromTriState("inherit")).toBeUndefined();
+    expect(fromTriState("on")).toBe(true);
+    expect(fromTriState("off")).toBe(false);
+  });
+});