v0.1.2 — progress bar with ETA

Long packs no longer run silently:

• New --progress flag (works on dnz a, x, and t) — renders a live bar on stderr with phase labels (planning / compressing / verifying / extracting), percent, elapsed time, and an ETA.
• The ETA is honest about backend speeds: progress is counted in weighted byte-units, with the slow context-mixing backend reporting incrementally every 64 KiB from its bit loops, so the bar moves smoothly through the slow tail instead of rushing to 90% and stalling. A sliding 10-second rate window adapts the ETA as the backend mix changes.
• Off by default — output is unchanged unless you pass --progress.

No format or compression changes — the instrumentation preserves byte order, so output is bit-identical to v0.1.1. Update with dnz update.

Full Changelog: v0.1.1...v0.1.2