feat: switch config to JSONC + split secrets.json

Load business config as JSONC (comments + trailing commas) via an
in-repo stripper then stdlib json — no new deps. Default path prefers
config.jsonc, falls back to legacy config.json. Auth write-back targets
only sibling secrets.json so JSONC comments are never wiped; secrets
overlay merges on load. Examples, compose, Docker, docs, favsort and
tools all share the same loader. Phase A only — no DB settings migration.

tools/import_fans_csv.py

@@ -31,6 +31,7 @@ from typing import Any, Mapping, Sequence
 ROOT = Path(__file__).resolve().parent.parent
 sys.path.insert(0, str(ROOT))
 
+from reaction_board.config import default_config_path  # noqa: E402
 from reaction_board.database import Database  # noqa: E402
 from reaction_board.repository import Repository  # noqa: E402
 from reaction_board.timeutil import SHANGHAI_TZ  # noqa: E402
@@ -226,19 +227,19 @@ def _database_path(config_path: str, override: str | None) -> Path:
         return Path(override)
     from reaction_board.config import ConfigStore
 
-    candidates = [Path(config_path), Path("/config/config.json")]
+    candidates = [Path(config_path), Path("/config/config.jsonc"), Path("/config/config.json")]
     for candidate in candidates:
         if candidate.exists():
             return ConfigStore(str(candidate), require_auth=False).get().storage.database_path
     raise ValueError(
-        "找不到配置文件；请用 --db /data/app.db 或 --config /config/config.json"
+        "找不到配置文件；请用 --db /data/app.db 或 --config /config/config.jsonc"
     )
 
 
 def main(argv: Sequence[str] | None = None) -> int:
     parser = argparse.ArgumentParser(description="从 B 站粉丝历史 CSV 回填 up_stat")
     parser.add_argument("--csv", required=True, help="粉丝历史 CSV 路径")
-    parser.add_argument("--config", default=str(ROOT / "config.json"), help="配置文件")
+    parser.add_argument("--config", default=str(default_config_path(ROOT)), help="配置文件")
     parser.add_argument("--db", default=None, help="直接指定数据库（覆盖配置）")
     parser.add_argument("--mid", type=int, default=DEFAULT_MID, help="写入的 B 站 mid")
     parser.add_argument("--force", action="store_true", help="覆盖同日期已有 ok=1 记录")