fix panic on extraction

[curious-rabbit]

A few bugs that cause panics or silently lose info

• ouch list panics on a corrupt .bz3 file because Bz3Decoder::new is called with .unwrap(). decompress.rs already uses ? for the same call.
• Tar compression panics if the file walker hits an I/O or permission error mid-walk (entry.unwrap() in archive/tar.rs). Zip and 7z already use ?.
• 7z extraction silently drops mtime-set errors via .unwrap_or_default(), so users get files with wrong timestamps and no warning.
• Typo in SUPPORTED_ALIASES: "tzlma" should be "tlzma" (every other place in the codebase uses tlzma).
• ouch panics at startup if the current directory is unreadable or has been deleted (env::current_dir().expect(...) in main.rs).
• --threads 0 is handled inconsistently: cli/mod.rs treats it as "auto" but commands/mod.rs still passes it to rayon, and build_global().unwrap() panics if the thread pool is already initialized.