UX fixes driven by cross-machine testing feedback:
- mode="auto" (new default) picks the filled input automatically, so users
no longer get "mode=file requires json_file" when they filled json_path
without switching the mode dropdown.
- json_file now renders as a dropdown of .json files under ComfyUI's
input/ directory (falls back to plain STRING if folder_paths or the
directory is unavailable).
- Surrounding quotes on json_path/json_file are stripped automatically —
Windows "Copy as Path" pastes quoted strings and that used to surface
as an opaque "file not found".
- Clearer errors for "no input" / "multiple inputs" in auto mode, and a
hint on path-not-found pointing at the quote issue.
Tests: 117 -> 121 (4 new auto-mode cases).
tack
de394c3f26