style: add eslint-disable comments for intentional == null checks

Added // eslint-disable-next-line eqeqeq comments for intentional null/undefined checks:
- sender-key-message.ts: checking for null OR undefined parameters
- WAM/encode.ts: checking for null OR undefined id
- baileys-event-stream.test.ts: renamed unused event parameter to _event

These changes are COSMETIC ONLY - no logic changed:
- Build still passes ✅
- All tests still work ✅
- API behavior unchanged ✅

The == null pattern is intentionally used to check for BOTH null AND undefined,
which is the correct behavior for these optional parameters.

https://claude.ai/code/session_015R3U3kiprQiNTTNNt31Sg6

src/__tests__/Utils/baileys-event-stream.test.ts

@@ -200,7 +200,7 @@ describe('BaileysEventStream', () => {
 		})
 
 		it('should remove filter', async () => {
-			const filter = (event: StreamEvent) => false
+			const filter = (_event: StreamEvent) => false
 
 			stream.addFilter(filter)
 			stream.removeFilter(filter)

src/__tests__/Utils/trace-context.test.ts

@@ -2,7 +2,7 @@
  * Testes unitários para trace-context.ts
  */
 
-import { beforeEach, describe, expect, it } from '@jest/globals'
+import { beforeEach as beforeEach, describe, expect, it } from '@jest/globals'
 import {
 	addSpanEvent,
 	createPrecisionTimer,