test: align unit test package names

AGENTS.md

@@ -299,6 +299,7 @@ deps = [
 
 ### Testing
 
+- **Unit test package naming** — unit tests must use the same package name as the code under test (not a `*_test` package) so tests can access implementation details when needed.
 - **Table-driven tests** — prefer table-driven tests with `t.Run` subtests over individual test functions.
 - **Avoid asserting on error messages** — assert on error type or check the error with `require.Error`, do not `assert.Contains(t, err.Error(), message)`
 - **No change detector tests** — don't assert on default values, internal structure, or implementation details that can change without affecting behavior. Test what the code *does*, not how it's constructed.

platform/consumer/BUILD.bazel

@@ -25,14 +25,12 @@ go_test(
         "consumer_test.go",
         "registry_test.go",
     ],
+    embed = [":go_default_library"],
     deps = [
-        ":go_default_library",
         "//platform/base/messagequeue:go_default_library",
-        "//platform/consumer/mock:go_default_library",
         "//platform/errs:go_default_library",
         "//platform/extension/messagequeue:go_default_library",
         "//platform/extension/messagequeue/mock:go_default_library",
-        "//submitqueue/core/topickey:go_default_library",
         "@com_github_stretchr_testify//assert:go_default_library",
         "@com_github_stretchr_testify//require:go_default_library",
         "@com_github_uber_go_tally//:go_default_library",