docs: inline how-to video embed (CDN attachment), drop committed binary

[hmanoor]

• README How-to guides section now showcases episode 01 with an inline-playing video (GitHub user-attachment CDN), matching the hero video mechanism
• docs/how-to/README.md embeds the same attachment and notes videos are CDN-hosted
• Removes docs/how-to/assets/ep01-first-launch-setup-wizard.mp4 — video binaries stay out of the open-source repo (clone weight); source of truth lives in the private repo

Docs-only change.

[github-actions]

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