feat(v1.8.1): Windows 兼容性修复 + SKILL.md 铁律区块

Windows 兼容性修复（基于真实使用痛点）:

- force_utf8_stdout(): 强制 stdout/stderr 为 UTF-8，修复 Windows GBK 崩溃（print('\\xa0') 不再炸）

- resolve_instances/load_config 新增 %APPDATA%/searxng-cli/ 路径，覆盖 Windows 配置约定

- fetch.py 失败诊断增强：输出 status_code=/cause=/url= 字段，AI Agent 可程序化区分 404/403/DNS 失败

SKILL.md 铁律区块（5 条，置顶）:

- stdout=数据/stderr=日志 永不混淆

- 禁用 2>/dev/null（丢弃 stderr = 失败时零诊断）

- 排错去 --quiet 加 --verbose

- 配置查找覆盖 WSL + Windows 双路径

- 实例 URL 必填，公共实例发现已移除

测试: 352 -> 362（新增 10 个：force_utf8_stdout 幂等性/GBK 替换/非 ASCII 打印/APPDATA 路径发现/txt 回退/空 APPDATA）

scripts/search.py

@@ -34,6 +34,7 @@ from common import (
     build_auth_headers,
     classify_error,
     emit_progress,
+    force_utf8_stdout,
     resolve_auth_basic,
     resolve_auth_bearer,
     set_progress_enabled,
@@ -329,13 +330,39 @@ def _read_instance_file(path: Path) -> list:
         return []
 
 
+def _windows_appdata_config_dir() -> Path:
+    """Return the Windows APPDATA config directory, or a sentinel Path if unset.
+
+    On Windows, the conventional per-user app config directory is
+    ``%APPDATA%`` (typically ``C:\\Users\\<user>\\AppData\\Roaming``).
+    On POSIX, this env var is unset and we return a sentinel
+    ``Path("/__no_appdata__")`` which never exists on disk, so the caller
+    can unconditionally append it to the candidate list without polluting
+    Linux/macOS lookups.
+
+    Note: ``Path("")`` resolves to ``.`` (current directory) on Windows,
+    which DOES exist — so we must use an absolute sentinel path instead.
+    """
+    appdata = os.environ.get("APPDATA", "")
+    if appdata:
+        return Path(appdata) / "searxng-cli"
+    # Sentinel: absolute path that never exists. Using "/" + unlikely name
+    # keeps it false on both POSIX and Windows (where "/" is the drive root).
+    return Path("/__no_appdata__")
+
+
 def resolve_instances(cli_arg: str = None) -> list:
     """Resolve instance URLs from (in priority order):
 
     1. ``--instance`` CLI flag (comma-separated list)
     2. ``SEARXNG_INSTANCE`` environment variable (comma-separated list)
-    3. config file: ``./searxng.toml`` → ``~/.config/searxng-cli/searxng.toml``
-       → ``./instances.txt`` → ``~/.config/searxng-cli/instances.txt``
+    3. config file search order:
+       a. ``./searxng.toml``
+       b. ``~/.config/searxng-cli/searxng.toml``
+       c. ``%APPDATA%/searxng-cli/searxng.toml``  (Windows only)
+       d. ``./instances.txt``
+       e. ``~/.config/searxng-cli/instances.txt``
+       f. ``%APPDATA%/searxng-cli/instances.txt``  (Windows only)
 
     Returns an empty list if no instance can be resolved.
     """
@@ -346,11 +373,14 @@ def resolve_instances(cli_arg: str = None) -> list:
     if env:
         return parse_instances(env)
 
+    win_dir = _windows_appdata_config_dir()
     candidates = [
         Path.cwd() / "searxng.toml",
         Path.home() / ".config" / "searxng-cli" / "searxng.toml",
+        win_dir / "searxng.toml",
         Path.cwd() / "instances.txt",
         Path.home() / ".config" / "searxng-cli" / "instances.txt",
+        win_dir / "instances.txt",
     ]
     for p in candidates:
         if p.exists():
@@ -395,9 +425,11 @@ def load_config(config_path: str = None) -> dict:
         except Exception as e:
             logger.warning(f"Warning: cannot read config '{p}': {e}")
             return {}
+    win_dir = _windows_appdata_config_dir()
     candidates = [
         Path.cwd() / "searxng.toml",
         Path.home() / ".config" / "searxng-cli" / "searxng.toml",
+        win_dir / "searxng.toml",
     ]
     for p in candidates:
         if p.exists():
@@ -1379,6 +1411,7 @@ def main():
     pre_args, _ = pre.parse_known_args()
 
     setup_logging(verbose=pre_args.verbose, quiet=pre_args.quiet)
+    force_utf8_stdout()  # Windows: prevent GBK crash on non-ASCII chars
 
     # Load config defaults from --config file, else ./searxng.toml or
     # ~/.config/searxng-cli/searxng.toml. Every CLI flag below can be