Implement tdrive file server

[tinysec]

Summary

• add the Go-based tdrive HTTP/WebDAV/FTP file server implementation
• add web UI assets, i18n, Dockerfile, README, and GitHub Actions build/release workflow
• fix the status bar separator so it renders as a middle dot instead of the wrong Chinese character
• close the os.Root-backed store in tests/app shutdown to avoid Windows temp directory cleanup failures

Tests

• go test ./...