refactor(lint): read the AI model vars through the cache in the quant check

test_local_model_quant_pinned opened group_vars/all/16_ai.yml twice per run,
once with yaml.safe_load for the entries and once with read_text to find an
alias line, so the file was parsed again for a check that several other lints
already read it for. test_no_uncached_file_reads rejects that, and it rejected
this module: restoring the previous version fails
test_modules_in_scope_use_cached_read_text, and the current one passes it.

load_yaml and read_text from utils.cache memoise by absolute path. The
'or {}' guard goes with the raw loader rather than being dropped silently:
load_yaml returns a mapping or raises TypeError on any other root, so .get
cannot meet None, and a malformed file now fails at this lint instead of
reading as an empty model list that the check would pass over.

d7bd200da1 on feature/store-i18n applies the same idiom to five other modules.
The two do not overlap: that branch cannot carry this file, which 499f8a4445
created here, so the sweep there and this commit together leave one pattern
rather than two.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

tests/lint/ansible/variables/test_local_model_quant_pinned.py

@@ -29,9 +29,9 @@ from __future__ import annotations
 import unittest
 from typing import ClassVar
 
-import yaml
-
 from utils.annotations.suppress import is_suppressed_at
+from utils.cache.files import read_text
+from utils.cache.yaml import load_yaml
 
 from . import PROJECT_ROOT
 
@@ -41,15 +41,12 @@ _KEY = "AI_LOCAL_MODELS"
 
 
 def _entries() -> list[dict]:
-    data = yaml.safe_load(_VARS_FILE.read_text(encoding="utf-8")) or {}
-    declared = data.get(_KEY)
+    declared = load_yaml(_VARS_FILE).get(_KEY)
     return [entry for entry in (declared or []) if isinstance(entry, dict)]
 
 
 def _line_of(alias: str) -> int:
-    for number, line in enumerate(
-        _VARS_FILE.read_text(encoding="utf-8").splitlines(), 1
-    ):
+    for number, line in enumerate(read_text(str(_VARS_FILE)).splitlines(), 1):
         if f"alias: {alias}" in line:
             return number
     return 0