Add HostManager for host records and host tokens

controller.hosts is now a HostManager wrapping the hosts datastore, the
same way controller.users wraps the users datastore. It owns creating
hosts (moved from HostPairingManager), revoking them (moved from
ControlConnection) and signing and verifying host tokens (moved from
Controller, generateHostToken is renamed signHostToken to match
signUserToken).

UserManager gains verifyUserToken, replacing the copies of the user
token check in WsServer and routes. The WsServer copy accepted a token
without iat when the user had no tokenValidAfter; the shared check
always requires iat, which jsonwebtoken adds by default.

Follows Cooldude2606's comment on #1161.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

test/controller/UserManager.test.js

@@ -135,6 +135,31 @@ describe("controller/UserManager", function () {
 		});
 	});
 
+	describe(".verifyUserToken()", function () {
+		const secret = () => Buffer.from(config.get("controller.auth_secret"), "base64");
+
+		it("should return the user the token was signed for", function () {
+			const user = userManager.createUser("Judy");
+			assert.equal(userManager.verifyUserToken(userManager.signUserToken(user)).id, user.id);
+		});
+		it("should reject a token for an unknown user", function () {
+			const token = userManager.signUserToken({ id: "nobody" });
+			assert.throws(() => userManager.verifyUserToken(token), new Error("invalid user"));
+		});
+		it("should reject a token issued before tokenValidAfter", function () {
+			const user = userManager.createUser("Mallory");
+			const token = jwt.sign({ aud: "user", user: user.id, iat: user.tokenValidAfter - 1 }, secret());
+			assert.throws(() => userManager.verifyUserToken(token), new Error("invalid token"));
+		});
+		it("should reject host tokens and bad signatures", function () {
+			const user = userManager.createUser("Niaj");
+			const hostToken = jwt.sign({ aud: "host", host: 5 }, secret());
+			assert.throws(() => userManager.verifyUserToken(hostToken), /audience invalid/);
+			const forged = jwt.sign({ aud: "user", user: user.id }, "wrong secret");
+			assert.throws(() => userManager.verifyUserToken(forged), /invalid signature/);
+		});
+	});
+
 	describe(".clearStatsOfInstance()", function () {
 		it("should clear instance stats for all users", function () {
 			const instanceId = 42;