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>

src/services/config_service.py

@@ -26,13 +26,16 @@ DEFAULT_CONFIG = {
     "outfit_resolution": "1K",
     "outfit_quality": "均衡",
     "outfit_retry_failed": False,
+    "outfit_prompt_name": "默认",  # last-selected 话术模板 name (docs/11 §7.2)
 }
 
 _CONFIG_FILENAME = "app_config.json"
 _AI_MODELS_FILENAME = "ai_models.json"
-_OUTFIT_PROMPT_FILENAME = "outfit_prompt.txt"
+_OUTFIT_PROMPT_FILENAME = "outfit_prompt.txt"        # legacy single prompt (migrated)
+_OUTFIT_PROMPTS_FILENAME = "outfit_prompts.json"     # multi named templates (§7.2)
+DEFAULT_OUTFIT_PROMPT_NAME = "默认"
 
-# Default outfit prompt (docs/11 §7). Persisted to outfit_prompt.txt on first save.
+# Default outfit prompt (docs/11 §7). Seeded into outfit_prompts.json on first run.
 DEFAULT_OUTFIT_PROMPT = (
     "为商品「{title}」生成人物上身实穿效果图：真人模特正面穿着这件衣服，"
     "完整保留款式、版型、颜色与印花图案，自然光、纯色棚拍背景，"
@@ -139,3 +142,51 @@ def save_outfit_prompt(text):
         logger.info("Outfit prompt saved to %s", prompt_file)
     except OSError as exc:
         logger.error("Failed to save outfit prompt to %s: %s", prompt_file, exc)
+
+
+def _normalize_prompts(data):
+    """Keep only valid {name, text} entries (non-empty name, string text)."""
+    if not isinstance(data, list):
+        return []
+    out = []
+    for item in data:
+        if isinstance(item, dict):
+            name = str(item.get("name", "")).strip()
+            text = item.get("text", "")
+            if name and isinstance(text, str):
+                out.append({"name": name, "text": text})
+    return out
+
+
+def load_outfit_prompts():
+    """Load named 话术 templates (docs/11 §7.2); always returns >= 1.
+
+    Missing/corrupt → migrate the legacy outfit_prompt.txt into a single
+    「默认」template, or seed it from DEFAULT_OUTFIT_PROMPT.
+    """
+    from services.file_service import get_config_path
+    prompts_file = get_config_path(_OUTFIT_PROMPTS_FILENAME)
+    if prompts_file.exists():
+        try:
+            with open(str(prompts_file), encoding="utf-8-sig") as f:
+                prompts = _normalize_prompts(json.load(f))
+            if prompts:
+                return prompts
+        except (json.JSONDecodeError, ValueError, OSError) as exc:
+            logger.warning("Outfit prompts unreadable (%s): %s", exc, prompts_file)
+
+    # Seed / migrate (load_outfit_prompt reads the legacy txt or the default).
+    return [{"name": DEFAULT_OUTFIT_PROMPT_NAME, "text": load_outfit_prompt()}]
+
+
+def save_outfit_prompts(prompts):
+    """Persist named 话术 templates as JSON (utf-8, no BOM). Does not raise."""
+    from services.file_service import get_config_path
+    prompts_file = get_config_path(_OUTFIT_PROMPTS_FILENAME)
+    try:
+        prompts_file.parent.mkdir(parents=True, exist_ok=True)
+        with open(str(prompts_file), "w", encoding="utf-8") as f:
+            json.dump(list(prompts), f, ensure_ascii=False, indent=2)
+        logger.info("Outfit prompts saved to %s", prompts_file)
+    except OSError as exc:
+        logger.error("Failed to save outfit prompts to %s: %s", prompts_file, exc)