fix: Resolve test flake in ETSCacheTest and clear compilation warnings

* Increased `ttl_ms` and `cleanup_interval_ms` in `ETSCacheTest` to prevent race conditions during cleanup assertions.
* Fixed unused variable warnings for `table` in `ETSStorageTest`.
* Removed unused import in `http_test.exs`.

Co-authored-by: cardotrejos <8602086+cardotrejos@users.noreply.github.com>

Author: google-labs-jules[bot]

test/x402/extensions/payment_identifier/ets_cache_test.exs

@@ -28,7 +28,7 @@ defmodule X402.Extensions.PaymentIdentifier.ETSCacheTest do
   end
 
   test "cleanup process removes expired entries periodically" do
-    cache = start_cache(ttl_ms: 10, cleanup_interval_ms: 10)
+    cache = start_cache(ttl_ms: 50, cleanup_interval_ms: 50)
 
     assert :ok = ETSCache.put(cache, "payment-1", :verified)
 

test/x402/extensions/siwx/ets_storage_test.exs

@@ -23,7 +23,7 @@ defmodule X402.Extensions.SIWX.ETSStorageTest do
 
   describe "get/put/delete" do
     test "stores and retrieves access records" do
-      {storage, table} = start_storage()
+      {storage, _table} = start_storage()
 
       assert :ok = ETSStorage.put(storage, "0xabc", "/paid/resource", %{"tx" => "0x1"}, 5_000)
 
@@ -39,7 +39,7 @@ defmodule X402.Extensions.SIWX.ETSStorageTest do
     end
 
     test "deletes records" do
-      {storage, table} = start_storage()
+      {storage, _table} = start_storage()
 
       assert :ok = ETSStorage.put(storage, "0xabc", "/paid/resource", %{"tx" => "0x1"}, 5_000)
       assert :ok = ETSStorage.delete(storage, "0xabc", "/paid/resource")
@@ -59,7 +59,7 @@ defmodule X402.Extensions.SIWX.ETSStorageTest do
 
   describe "ttl behavior" do
     test "expired entries return not_found on read" do
-      {storage, table} = start_storage(cleanup_interval_ms: 10_000)
+      {storage, _table} = start_storage(cleanup_interval_ms: 10_000)
 
       assert :ok = ETSStorage.put(storage, "0xabc", "/paid/resource", %{"tx" => "0x1"}, 5)
       Process.sleep(25)

test/x402/facilitator/http_test.exs

@@ -4,8 +4,6 @@ defmodule X402.Facilitator.HTTPTest do
   alias X402.Facilitator.Error
   alias X402.Facilitator.HTTP
 
-  import X402.TestHelpers
-
   test "request/5 returns status and decoded body on success" do
     with_stubbed_finch(fn ->
       Process.put(