feat(seeder): scenario-aware HTML reports, cookbook test set, misc clean-ups

[anotherjesse]

Seeder:

• Replace inline string‐built report with template engine (templates/*)
  • Summary bar, per-scenario sections, graceful no-screenshot fallback
  • New ExecutedScenario type; CLI now tracks results per step & scenario
• Add 10-scenario “Family Cookbook” generator for wider import/extend coverage
• CLI hardening
  • Per-step try/catch + skip-on-fail logic
  • Longer wait before screenshot
• Misc fixes & polish

(next round of fixes will ship in a separate PR)

[anotherjesse]

hmm, the code isn't that bad!