test(compose): treat ./.state/ bind mounts as runtime state, like ./data/

main's CI test job has failed on every push since 2026-09-24: the llm
service mounts ./.state/comments and ./.state/llm/pdfcache, which are
gitignored runtime state and absent from a fresh checkout, and
test_all_relative_bind_mounts_exist only exempted ./data/. With
`pytest -x` that one failure also hid the coverage gate.

Refs #1365

tests/test_compose_mounts.py

@@ -45,9 +45,10 @@ class TestBindMountSourcesExist:
 
         missing = []
         for svc, host_path, full in mounts:
-            # ./data/ is gitignored runtime state — populated by service
-            # bootstrap on first run, not present in a fresh checkout (CI).
-            if host_path.startswith("./data/"):
+            # ./data/ and ./.state/ are gitignored runtime state — populated
+            # by service bootstrap on first run, not present in a fresh
+            # checkout (CI).
+            if host_path.startswith(("./data/", "./.state/")):
                 continue
             resolved = ROOT / host_path
             if not resolved.exists():