oshwhub: pin listing index snapshot (33,695 rows, 29 MB) into git

Previous commit added the dump script + report but the actual jsonl was caught
by data/state/* gitignore. Add a targeted exception so the snapshot travels with
the repo — anyone who clones can do local filtering without re-hitting the API.

The data is regenerable (scripts/dump_listing_index.py is one-shot, ~1 min), but
pinning a dated snapshot lets us reason about "the state of the corpus on
2026-04-28" reproducibly. Future re-dumps overwrite the same path.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.gitignore

@@ -3,6 +3,8 @@ data/processed/*
 data/state/*
 !data/processed/.gitkeep
 !data/state/.gitkeep
+# 例外：oshwhub 全量 listing 索引快照入库（28 MB jsonl，可重抓但要钉个版本）
+!data/state/oshwhub_listing_full.jsonl
 
 # data/raw 入库（工程二进制走 LFS，见 .gitattributes）