fix(vfs): emit warnings when tar extraction skips unsupported entry types

[chaliy]

Summary

• Tar extraction now warns on stderr when symlink (type 2), hard link (type 1), and other unsupported entry types (char/block devices, FIFOs, etc.) are skipped during extraction
• Previously these entries were silently discarded with no indication to the user
• Added three tests: test_tar_extract_symlink_warning, test_tar_extract_hardlink_warning, test_tar_extract_unsupported_type_warning

Closes #1178

Test plan

• cargo test -p bashkit -- tar — all 23 tar tests pass (13 existing + 3 new)
• cargo fmt --check — clean
• cargo clippy --all-targets --all-features -- -D warnings — clean