Build the crash-survival multi-repo demo (asciinema + README section)

[stempeck]

Stage 1. Named Stage-1 deliverable in the strategy doc; it is the content for the Show HN and the comparison page.

Evidence

• No runnable/viewable demo artifact exists anywhere in the tree — docs/recovery-model.md describes the model, nothing shows it. [verified: git trees API sweep for bench/demo paths, 2026-08-09]
• Claude Code Agent Teams documents "no session resumption of in-process teammates" and no worktree isolation for teammates — the demo shows something the first-party feature explicitly cannot do today. [verified: https://code.claude.com/docs/en/agent-teams.md]

Acceptance criteria

• Scripted scenario: formula running across two repos; agent killed (-9) mid-step; af up resumes at the exact step with identity intact
• Recorded as asciinema (primary) with a GIF fallback embedded in README
• Repeatable: demo/ directory with the script so viewers can run it themselves
• Honest framing: state what is NOT shown (e.g. no cross-machine resume)

Filed by the product-manager cycle af-147a1678; approved by operator: #98 (comment)