fix(companion): validate runtime and heartbeat loop options

src/companion/heartbeatLoop.test.ts

@@ -37,6 +37,16 @@ describe('CompanionHeartbeatLoop', () => {
     loop.stop();
   });
 
+  it('validates constructor options', () => {
+    const publisher = { publishHeartbeat: vi.fn(async () => buildStatusResult()) };
+    expect(() => new CompanionHeartbeatLoop(publisher, { intervalMs: 0 })).toThrow(
+      'intervalMs must be a positive number',
+    );
+    expect(() => new CompanionHeartbeatLoop(publisher, { maxConsecutiveFailures: 0 })).toThrow(
+      'maxConsecutiveFailures must be >= 1 when specified',
+    );
+  });
+
   it('supports delayed first run when runImmediately=false', async () => {
     const publishHeartbeat = vi.fn(async () => buildStatusResult());
     const loop = new CompanionHeartbeatLoop({ publishHeartbeat }, { intervalMs: 500 });