feat(ai-outfit): multiple named prompt templates (§19.8)

- config_service: outfit_prompts.json load/save (utf-8-sig read, no-BOM write,
  corrupt/empty -> migrate legacy outfit_prompt.txt or seed 默认; always >=1;
  _normalize_prompts drops invalid). app_config gains outfit_prompt_name.
- ai_outfit_panel: 通用话术 group gets a template dropdown + 新建/另存为/重命名/
  删除 (keeps 插入标题/保存). Switching loads the template + refreshes preview;
  dirty edits prompt Save/Discard/Cancel before switching/new/save-as (cancel
  reverts the combo); unique names; can't delete the last one; selection
  persisted via config_changed; 开始生成 stores the editor into the template.
- tests: +6 config cases (14 total); offscreen CRUD/dirty/rename/delete verified;
  full suite (12 files) green.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/test_config_service.py

@@ -68,6 +68,49 @@ class TestOutfitConfigHelpers(unittest.TestCase):
         raw = (self.config_dir / "outfit_prompt.txt").read_bytes()
         self.assertFalse(raw.startswith(b"\xef\xbb\xbf"))
 
+    # -- outfit_prompts.json (multi templates, §7.2) --------------------
+
+    def test_prompts_seed_default_when_missing(self):
+        prompts = cs.load_outfit_prompts()
+        self.assertEqual(len(prompts), 1)
+        self.assertEqual(prompts[0]["name"], cs.DEFAULT_OUTFIT_PROMPT_NAME)
+        self.assertEqual(prompts[0]["text"], cs.DEFAULT_OUTFIT_PROMPT)
+
+    def test_prompts_migrate_legacy_txt(self):
+        (self.config_dir / "outfit_prompt.txt").write_text(
+            "旧话术 {title}", encoding="utf-8")
+        prompts = cs.load_outfit_prompts()
+        self.assertEqual(len(prompts), 1)
+        self.assertEqual(prompts[0]["name"], "默认")
+        self.assertEqual(prompts[0]["text"], "旧话术 {title}")
+
+    def test_prompts_roundtrip_and_no_bom(self):
+        data = [{"name": "A", "text": "甲 {title}"}, {"name": "B", "text": "乙"}]
+        cs.save_outfit_prompts(data)
+        self.assertEqual(cs.load_outfit_prompts(), data)
+        raw = (self.config_dir / "outfit_prompts.json").read_bytes()
+        self.assertFalse(raw.startswith(b"\xef\xbb\xbf"))
+
+    def test_prompts_corrupt_falls_back(self):
+        (self.config_dir / "outfit_prompts.json").write_text("{ bad", encoding="utf-8")
+        prompts = cs.load_outfit_prompts()
+        self.assertEqual(len(prompts), 1)
+        self.assertEqual(prompts[0]["name"], cs.DEFAULT_OUTFIT_PROMPT_NAME)
+
+    def test_prompts_drop_invalid_entries(self):
+        import json
+        (self.config_dir / "outfit_prompts.json").write_text(
+            json.dumps([{"name": "", "text": "x"}, {"name": "ok", "text": "y"},
+                        {"name": "bad", "text": 5}, "nope"]), encoding="utf-8")
+        prompts = cs.load_outfit_prompts()
+        self.assertEqual(prompts, [{"name": "ok", "text": "y"}])
+
+    def test_prompts_tolerate_bom(self):
+        import json
+        (self.config_dir / "outfit_prompts.json").write_bytes(
+            "".encode("utf-8") + json.dumps([{"name": "z", "text": "t"}]).encode("utf-8"))
+        self.assertEqual(cs.load_outfit_prompts()[0]["name"], "z")
+
 
 if __name__ == "__main__":
     unittest.main()