Merge fix/tests/dockerignore-lint-conformance into feature/store-i18n

Maintainer's main hotfix 8860074807: test_dockerignore.py from #1384 imports PROJECT_ROOT from the package and reads through utils.cache.files, so test_project_root_import and test_no_uncached_file_reads pass (gate pass 1 on d9c278ce46 red on both).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/lint/repository/test_dockerignore.py

@@ -1,27 +1,29 @@
 import re
 import unittest
-from pathlib import Path
 
-PROJECT_ROOT = Path(__file__).resolve().parents[3]
+from utils.cache.files import read_text
+
+from . import PROJECT_ROOT
+
 NESTED_CHECKOUTS = (".claude/worktrees/", ".worktrees/")
 
 
 class TestDockerignore(unittest.TestCase):
     def test_dockerignore_is_the_gitignore(self) -> None:
         self.assertEqual(
-            (PROJECT_ROOT / ".gitignore").read_text(),
-            (PROJECT_ROOT / ".dockerignore").read_text(),
+            read_text(str(PROJECT_ROOT / ".gitignore")),
+            read_text(str(PROJECT_ROOT / ".dockerignore")),
             "Run 'make fix-dockerignore': .dockerignore must be a copy of .gitignore.",
         )
 
     def test_nested_checkouts_stay_out_of_the_build_context(self) -> None:
-        lines = (PROJECT_ROOT / ".dockerignore").read_text().splitlines()
+        lines = read_text(str(PROJECT_ROOT / ".dockerignore")).splitlines()
         for entry in NESTED_CHECKOUTS:
             with self.subTest(entry=entry):
                 self.assertIn(entry, lines)
 
     def test_compose_up_regenerates_the_dockerignore(self) -> None:
-        makefile = (PROJECT_ROOT / "Makefile").read_text()
+        makefile = read_text(str(PROJECT_ROOT / "Makefile"))
         match = re.search(r"^compose-up:(.*)$", makefile, re.MULTILINE)
         self.assertIsNotNone(match, "Makefile has no compose-up target")
         self.assertIn("fix-dockerignore", match.group(1).split())