docs: add Provenant-vs-ScanCode race demo to README

[mstykow]

Summary

• Add an animated side-by-side race GIF near the top of the README: Provenant and ScanCode scanning the same astral-sh/uv repository with identical flags (--license --package), one process each. Provenant finishes in ~6s (139 packages, 0 errors, compact summary) while ScanCode is still in early scan.
• Check in the reproducible docs/demo.tape (vhs, tmux two-pane layout) with documented prerequisites, including how the ScanCode Docker image is built via compare-outputs.
• Lightly de-hedge the project-status callout. No version numbers or exact benchmark averages added to the root README.

Issues

• Covers: README first-impression / discoverability; proves the speed claim visually rather than asserting it.
• Closes:

Scope and exclusions

• Included: README race GIF + caption, reproducible vhs tape, status-callout wording.
• Explicit exclusions: no code, CLI, or output-schema changes; no benchmark data changes.

How to verify

• Open the rendered README; confirm the two-pane GIF displays (ScanCode left, Provenant right) and the caption reads correctly.
• To regenerate, see the prerequisites documented at the top of docs/demo.tape, then vhs docs/demo.tape from the repo root.

Intentional differences from Python

• N/A

Follow-up work

• Stacked on feat(cli): show per-phase timing breakdown only under --verbose #1225 (per-phase timings behind --verbose); the race pane showcases that compact default output.
• Distribution channels (GitHub Action, Docker, Homebrew) deferred pending the org decision.

[greptile-apps]

Greptile Summary

This PR adds a README race demo for Provenant and ScanCode. The main changes are:

• A new side-by-side GIF in the README.
• Updated project status wording near the top of the README.
• A reproducible VHS tape for regenerating the demo.

Confidence Score: 5/5

This looks safe to merge.

• No blocking issues found in the changed code.

Important Files Changed

Filename	Overview
README.md	Adds the race GIF and updates the nearby status copy.
docs/demo.tape	Adds the reproducible demo recording workflow under the ignored scratch area.
docs/provenant-demo.gif	Adds the generated animation used by the README.

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