refactor(deep-research): replace case study company with ByteDance example

Replace \"深度推理（上海）科技有限公司\" with \"字节跳动子公司\"
as the case study example to avoid exposing user's own company info.

Also update .gitignore to exclude:
- deep-research-output/ (contains sensitive research data)
- recovered_deep_research/
- .opencli/
- douban-skill/ (work-in-progress)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

deep-research/SKILL.md

@@ -320,7 +320,7 @@ Report: `[P3 complete] {approved}/{total} sources. {N} domains. Official share:
 
 ### Handling Information Black Box
 
-When researching entities with no public footprint (like the "深度推理" example):
+When researching entities with no public footprint (like the "字节跳动子公司" example):
 
 **What an external researcher would find:**
 - WHOIS: Privacy protected → No owner info