chore: ignore dirty state in bats submodules

Set 'ignore = dirty' for tests/bats and test_helper submodules to prevent accidental
staging of test-time modifications. These submodules should never be committed with
changes — they're only for running the test suite locally.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

.gitmodules

@@ -1,12 +1,15 @@
 [submodule "tests/bats"]
 	path = tests/bats
 	url = https://github.com/bats-core/bats-core.git
+	ignore = dirty
 [submodule "tests/test_helper/bats-support"]
 	path = tests/test_helper/bats-support
 	url = https://github.com/bats-core/bats-support.git
+	ignore = dirty
 [submodule "tests/test_helper/bats-assert"]
 	path = tests/test_helper/bats-assert
 	url = https://github.com/bats-core/bats-assert.git
+	ignore = dirty
 [submodule "docs/wiki"]
 	path = docs/wiki
 	url = git@git.dev.rkdr.net:Defame1297/holocron.wiki.git