docs(readme): proof lines say what the page shows

[shhdwi]

Fixes the last README proof lines that said more than the page shows:

• "42% fewer tokens" is uncached input tokens in the 162-run benchmark.
• That benchmark ran an agent loop on Claude Sonnet, not Claude Code, so the summary table says "Cold agent / Agent with the graft map".
• "Up to 4x cheaper, 3x faster" on popular repos came from runs the README never shows. It now gives the PocketBase numbers that are on the page: 21% cheaper, 14% faster over 15 real tasks.

The how-it-works animation still draws "up to 4x tokens saved"; the new render from the site work replaces it.

🤖 Generated with Claude Code

[trailhq-graft]

🌱 graft blast radius

Nothing outside this diff depends on it. 0 areas changed; no indexed dependents at depth 2.

⚠️ 1 changed file not in the graph (README.md) — no parser claims the extension, or the index predates the file.

_{graft blast · refs/graft/base...HEAD · depth 2 · 1 changed file}

Open the interactive graph → — click an area to see the code that changed, and the line that reaches it.