Several file operations used os.ModePerm (0777) which makes files
world-writable and world-readable, violating the principle of least
privilege:
- database/db.go: InitDB directory creation → 0755
- xray/process.go: Xray config write → 0644
- xray/process.go: Crash report write → 0644
- web/service/server.go: Binary extraction → 0755
Also removes unused "io/fs" imports from the affected files.
Qiaochu Hu
24cd271486